LIBRARY OF CONGRESS^ 

W- ^'-f^ira 

UNITED STATES OF AMERICA. 



►,1 



lA 



1 



FRONTISPIECE. 




Fig. I. 

THE PHENOMENON OF "BARKING," AS MANIFESTED BY IRONS F AND Fx. (See Page 36.) 




r^.^^^ 



■/ 



Fig. 2. 
diffkrknce in appearance of fractures produced by impact, of varying degrees (^f 

ENERG\', I'Ml-: MATERIAL BEING THE SAME. (See Page 35.) 



Jliliutl/IHS Pr'niliii;! Cii. Iluetan. 



Bearvslee on Wrought-Iron and Chain-Cables. 



EXPERIMENTS 

ON THE 

STRENaTH OF WROUGHT-IEON 

AXD OF 

CHAIN-CABLES. 



REPORT OF THE COMMITTEES OF THE UNITED STATES BOARD 

APPOINTED TO TEST IRON, STEEL AND OTHER iMETALS, 

ON CHAIN-CABLES, MALLEABLE IRON, AND 

RE-HEATING AND RE-ROLLING 

WROUGHT-IRON; 

INCLUDING 

MISCELLANEOUS INVESTIGATIONS INTO THE PHYSICAL 

AND CHEMICAL PROPERTIES OF ROLLED 

WROUGHT-IRON. 



COMMANDER L^ A. BEARDSLEE, U.S.N., 

'C ^ ^ Member of the Board, and Chairman of the Committees. 

\^^ c 






BY 



WILLIAM ^vENT, M.E., 

Formerly Assistant to the Committee on Allorjs of the United States Board; 

Associate Editor of the ^^ American Manufacturer and 

Iron World," Pittsburgh, Penn. 









NEW YORK: 

JOHN WILEY AND SONS, 

15 AsTOR Place. 
1879. 



7r 






COPTRIGHT, 1879, 

By WILLIAM KENT. 



PREFACE. 



The Report of which the following pages are an abridgment was 
published by the United States Government in 1879, as part of 
Executive Document No. 98, House of Representatives, Forty-fifth 
Congress, Second Session. 

It forms an octavo of two hundred and sixtj'-seven pages, with 
thirteen hehotype-plates, and several wood-cuts. It is not only by 
far the most elaborate record of tests of wrought-iron and of chain- 
cables that has ever been given to the world, but it is the most 
valuable in results ; in describing newly observed phenomena, in 
tabulating variations of strength due to differences in methods of 
manufacture, and reveaUng their causes, in investigation of the effect 
of impact, in pointing out causes of defects in strength of both 
bars and cables, and generally in gi\^ng information that is of imme- 
diate practical value to manufacturers of iron and to engineers. 

As but a limited number of copies of the report were issued by the 
Government, and as it contains a large amount of detailed tabular 
matter, which, while necessary in an official report of this kind, to 
corroborate the conclusions deduced, is not necessar}^ to a full com- 
prehension of these conclusions, — it has been thought that an 
abridgment would be acceptable to many who would be unable to 
obtain the original work. 

The undersigned, in preparing the abridgment, has had the full 

consent of Commander Beardslee, and obtained his approval of " 

the manuscript prior to iDublication. 

WM. KENT. 
Pittsburgh, Pekn"., May, 1879. 



CONTENTS. 



SECTION I. 

Page 

Introduction 1 

The Bar. — Part 1 4 

Testing-Machines, and Methods of Testing 5 

Notes npon the "Records of Bars tested by Tension" . . . G 

Strengtli and Elastic Limit of Round Bar-Iron .... 8 

The Bar.— Part II 11 

Investigation of the Effect of Differences in the Amount of 

Reduction by the Rolls 11 

SECTION II. 

Part I. — Proper Form and Proportions of Test-Pieces . . 20 
Part II. — Comparative Strength of Bars in their Normal 
Condition, and as Reduced by Turning away the Skin and 
Adjacent Iron 27 

SECTION III. 

Tests of Bars by Impact; showing Action of Various Types of 

Iron under Sudden Strains . .31 

Method of testing by Impact 32 

Barking 36 

Crystallization 36 

Record of Impact Tests 37 

SECTION IV. 

A Paper describing a Series of Experiments to determine 
Facts in Regard to the Operation of the Law called the 
Elevation of the Limit of Stress 40 



VI CONTENTS. 



SECTION y. 

The Cable 49 

Experiments upon Comparative Strength of Studded and Unstud- 

ded Links 52 

Description of Method of testing Cables 54 

Weight of Chain-Cables 57 

Methods by 'svhieh the Weight of Chain-Cables can be reduced 
in a greater Ratio than the Strength . . . . . .58 

Comparison of Results obtained by Tension upon Sections of 
Cable-Links, and upon Bars of the Iron from which Links were 

made 62 

< 

SECTION YL 

Proof-Straixs for Chain-Cables 08 

Effects of the Use of Strains prescribed by the Admiralty Proof- 
Table G8 

Discussion of the Principles upon which Proof-Strains should be 

based 71 

Ratio of Strength of Sections of Links to that of the Bars from 

which they were made 72 

Probable Strength of Round Bars, calculated with an Allowance 

for Variation in Strength due to Variation in Diameter . . 77 
Probable Strength of Cables made from Bars of given Streiigth . 79 

Recommended Proof -Table 81 

Comparison of the Proof-Strains recommended, and the Strains 
in Use 81 

SECTION VIL 

Part I. — Notes upon the Irons examined 83 

Part II. — Comparison of Chemical and Physical Results . . 92 

Analyses of the Irons used in making Chain-Cables ... 93 
Relative Values of Iron in Bars, in Tenacity, Reduction of Area, 

and Elongation, and in Proportion of Chain to Bar ... 95 
Summary of the Principal Physical and Chemical Properties of 

Sixteen Irons 90 

Effects of Phosphorus 97 

Effects of Silicon 101 

Effects of Carbon 102 

Effects of Manganese, Copper, Nickel, Cobalt, Sulphur, and Slag, 105 

Welding 100 

What is learned from Chemical Analyses 113 

Conclusions derived from a Comparison of Chemical and Physical 

Results 117 



REPORT 



OP THE 



EESULTS or INVESTIGATIONS MADE BY COMMITTEES D, H, AND 

M, OE THE UNITED-STATES BOAED APPOINTED TO 

TEST lEON, STEEL, AND OTHEE METALS. 



SECTION I. 
INTRODUCTION. 



The investigations assigned to the three committees desig- 
nated by the letters D, H, and M were as follows : — 

To Committee D, " On Chain and Wire Ropes," with instruc- 
tions " to determine the character of iron best adapted for 
chain cables, the best form arid proportions of link, and the 
qualities of metal used in the manufacture of iron and steel 
wire rope." 

To Committee H, " On Iron, Malleable," with instructions "to 
examine and report upon the mechanical and physical proper- 
ties of wrought-iron." 

To Committee M, " On Re-heating and Re-rolling," with in- 
structions " to examine and report upon the effects of re-heat- 
ing and re-rolling, or otherwise re-working, of hammering as 
compared with rolling, and of annealing the metals." 

The work thus assigned to three different committees was 
of such a -nature, that experiments made by any one of them 
would necessarily furnish data which would prove of value to 



2 WROUGHT-IRON AND CHAIN-CABLES. 

all ; and as the three committees consisted of but five members 
of the board, one of whom was chairman of all, it was consid- 
ered advisable, in order to economize time, labor, and means 
by the avoidance of duplication of expensive experiments, and 
of making duplicate and triplicate reports of the same series, 
to consolidate the committees, and to conduct the investigations 
in such a manner that a single report would cover the whole 
ground. In thus concentrating the work, it was necessary that 
a leading object should be selected, and it was considered that 
the research required to establish the characteristics of iron 
best adapted for the manufacture of cables would furnish data 
which would bear more or less upon the subjects to be investi- 
gated by Committees H and M ; while it would be quite practi- 
cable to select from the wide field presented by "wrought- 
iron," and differences in methods of treating it, any number 
of lines of research, none of which would prove of much ser- 
vice in establishing points in regard to chain-iron. 

Our experiments, therefore, have been all so carried out, that 
while we have been able to obtain data, both as to the mechan- 
ical and physical properties of wrought-iron, and as to the 
effects of different methods of treatment of the raw material, 
all have been made to contribute their quota toward the estab- 
lishment of methods by which an iron could be judged cor- 
rectly as to its adaptability for chain-cable manufacture. Such 
points well established would prove to possess value, not only 
to the manufacturers and purchasers of cables and cable-iron, 
but also to manufacturers of iron bridges and other construc- 
tions, which, like the cable, depend for their value upon their 
power of resisting to the utmost destroying forces of various 
and irregular natures. 

In submitting this report, we would say that the extent of 
our investigations has been restricted by narrowness of our 
means, and the necessity which has arisen that we should sub- 
mit the results of such work as we have accomplished. They 
but point the way toward a thorough re-examination of the 
subjects involved, which, based upon our results, would provide 



INTRODUCTION. 3 

a valuable mass of information, to which this report would 
occupy the relation of a preface. 

The cable-link is but a modification of the round rolled bar, 
and its qualities must depend upon those of the bar from which 
it is made. Therefore we have selected the eound bar as the 
foundation of our work ; and our endeavor has been to ascertain 
what qualities should be inherent in it, and which should re- 
main without deterioration through various processes incident 
to the manufacture from it of finished products of other forms. 

Cables in service are subject to the destroying forces of sud- 
den strains, alternations of sudden and steady heavy strains, 
heavy steady strains, abrasion, and corrosion ; and the danger 
from each takes precedence in the order given. 

The relative importance of these sources of danger indicates 
that iron which is best adapted for cables is that which pos- 
sesses great power to resist both sudden and steady strains, and 
that neither of these qualities in excess will compensate for a 
deficiency in the other. 

The strength of the cable is but that of the weakest link, and 
the strength of this link but that of the ivealcest part : therefore, 
in order that a cable shall be strong and reliable, the weakest 
part of the weakest link must be made as strong as possible. 

The weakest part of nearly every link is the weld. With 
certain types of iron the weld is much weaker than with others: 
hence we consider that the prime elements of value in a cable- 
iron are power to i^esist sudden strains, and to be welded thor- 
oughly without loss of strength. By the former we insure 
against the greatest danger, and by the latter against the 
frequently repeated ordinary dangers. 

We Avere not able to obtain any information of value as to 
the qualities of various American irons in these two respects ; 
and we therefore resolved upon making a series of experimental 
investigations, by the results of which we hoped to be able to 
form a correct judgment. 



4 WKOUGHT-IRON AND CHAIN-CABLES. 

THE BAR. — PART I. 

Our plan of investigation was to first ascertain, by means of 
tension tests made upon bars of such irons as we could procure, 
the amount of strength, elasticity, &c., which would be found 
to exist in ordinary American bar iron ; next, by tests by im- 
pact upon the same irons, to ascertain their relative powers to 
resist sudden strains; and finally, having ascertained these 
essential points in the material^ to make from each iron a num- 
ber of cable-links, and by tension to find their strength and 
uniformity, and the degree of dependence to be placed upon 
the ivelds. 

To carry out these investigations, we procured bars of round 
iron of sizes such as are usually used in the manufacture of 
cables ; viz., from two-inch diameter to one inch, from the fol- 
lowing rolling-mills and dealers in iron, viz., Burden & Sons of 
New York, Bentoni of Pennsylvania, Burgess of Ohio, Cata- 
sauqua of Pennsylvania, New-Jersey Iron and Steel Company 
of New Jersey, Niles Iron Company of Ohio, Phoenix of 
Pennsylvania, Pembroke of Massachusetts, Pencoyd of Penn- 
sylvania, Tredegar of Virginia, Trego and Thompson of ]Mary- 
land, Sligo of Pennsylvania, Tamaqua of Pennsylvania, Wyeth 
Brothers of ^Maryland, and many other bars of unknown 
origin. 

The experiments, upon the results of which our report is 
based, comprise the details of all physical phenomena observed 
by us while testing to destruction nearly two thousand bar test- 
pieces by the strain of tension, over fifteen hundred by the 
strain of percussion, and nearly five hundred cable-links, made 
in all respects as for service. 

Tlie tension-tests upon bars were made both upon bars in 
their normal condition, and upon others from wdiich a portion 
of the surface had been turned away. Those by impact were 
made upon portions of the same bars which had been tested 
by tension, and those upon chain-links from other portions of 
the same bars. The Navy Department placed at our service 



THE BAE. 5 

the facilities of the Washington Navy Yard, which included 
the use of forges and of two testing-machines for making 
tension-tests ; also of such records as we desired, and of a large 
quantity of contract chain-iron, which it was deemed advisable 
to examine. 

A brief description of our testing-machines, and of our 
methods of testing, with a few physical phenomena we have 
observed, will enable the terms used in the report to be under- 
stood. 

Testing-Machines, and Methods of Testing. 

In order that we might obtain the tensile strength, elastic 
limit, ductility, &c., of round bars, our first test was by tension 
upon full-sized bars, from which the outer portion had not been 
removed. These tests were made by means of the " chain- 
proving machine," at the Washington Navy Yard, which in this 
report is called " testing-machine A." This machine consists 
of a long trough, in which a fifteen-fathom section of cable can 
be stretched by means of a hydraulic pump, to which it is con- 
nected at one end, while the other end is made fast to a holder, 
which in turn connects with a system of levers, by which the 
stress is weighed by means of weights placed upon a platform 
at the extremity of the long lever. 

The capacity . of the machine is three hundred thousand 
pounds, and the levers are so adjusted that a weight of one 
pound upon the platform balances two hundred pounds of 
stress. 

The pieces to be tested were sections of the bar at least eight 
times the diameter in length, and originally fitted with loops of 
larger-sized iron, welded to the ends. 

Additional tests by tension were made, upon many of the 
irons by means of cylindrical test-pieces turned from the bars, 
and ruptured by the " Rodman Dynamometer," called in this 
report " testing-machine B." 

The results obtained by this machine agree very closely, in 
some cases, with those obtained by testing-machine A, and in 



6 T7E0UGHT-IE0X AND CHAIN-CABLES. 

others differ widely. A portion of these differences is probably 
due to differences in the accuracy of the two machines and 
methods, and others to a natural difference in the character 
of the metal as developed by the entire bar, and by a portion 
of the core and adjacent iron. 

This machine holds the specimen to be tested by means of 
clamps. 

The capacity of the machine is one hundred thousand pounds, 
and it will weigh a stress of ten pounds with accuracy. 

Notes upon the " Records of Baes tested by Tension." 

Column headed " Diameter.^' — The strength per square inch 
of a bar, as deduced from the stress at which the entire bar has 
been torn asunder, cannot be correctly ascertained, except the 
diameter of the bar be carefully calipered : the nominal size 
and the exact size seldom coincide ; and at times we have found 
variations of four-hundredths of an inch, which variation is 
sufficient to produce important errors. 

Ai^eas, — The " original area " is that which corresponds to 
the diameter of the piece before test; the "reduced area" cor- 
responds with the least diameter after rupture ; the " tensile 
limit area " corresponds with the least diameter at the highest 
stress the piece sustains. 

Length. — The length of the clear cylindrical portion be- 
tween punch-marks is measured before the stress is applied, 
and after fracture. In testing with the machine B it is also 
measured at the " tensile limit." 

Percentage of Elongation. — This element, as given in many 
tables, is of little value, the percentage being greatly dependent 
upon the original length of the specimen. When this is not 
given, the percentage is of no value. 

The following experiment will make this clear : From a bar 
of \%" iron, of very uniform character, three test-pieces were 
prepared, which were in all respects similar, except in length. 
The first was 75, the second 20, and the third 10 inches long. 



THE BAR. 7 

They were pulled asunder, and the first was found to have 
elongated 14 inches, or 18.64 per cent of the original length ; 
the second had elongated 4.36 inches, or 21.8 per cent ; and the 
third 2.22 inches, or 22.2 per cent. Our records supply many 
confirmatory results. 

First Stretch. — The .bar being fastened to the holders, a 
pair of large dividers was adjusted to punch-marks, and the 
stress slowly applied ; at the instant the elongation was suf- 
ficient to draw one punch-mark clear of the dividers' point, the 
stress was weighed, and recorded as first stretch. 

Ultimate stress is the stress which represents the highest 
which has been withstood by the specimen ; but it was not the 
amount which finally produced the rupture : this stress pro- 
duced a weakening, from which, had the specimen been rested, 
it would have recovered ; by continuing it, the specimen finally 
parted at much less. 

' Original^ Fractured^ and Tensile Limit Areas, — The measure- 
ments taken at the "tensile limit" introduce a new method 
by which the comparative values of different irons may be 
estimated. 

Ordinarily the tenacity of iron is expressed in the strength 
per square inch of the sectional area of the test-piece before 
its form has been changed by stress. 

Kirkaldy suggested, as a more just method, that the area 
corresponding to the diameter of the fractured surfaces should 
be adopted as the limit of measurement. 

Our experiments lead us to believe that between these 
extremes of original and fractured areas there is an inter- 
mediate area which can be used with profit, which is that 
which corresponds ivith the least diameter of the test-piece at the 
stress ivhich marks the highest point of resistance to continually/ 
increasing strains. This point we have termed the " tensile 
limit. ^^ 

There are practical difficulties encountered in measuring 
accurately the diameter of the fractured surfaces. After the 
test-piece has been pulled asunder, there is a difficulty in joining 



8 WROUGHT-IEON AND CHAIX-CABLES. 

perfectly the two fractured surfaces, and frequently the line of 
surface is not at right angles with the axis of the cylinder : this 
necessitates two measurements, — one of the greatest and one 
of the least diameter, and an interpolation, — and, in making 
these measurements, there are chances of error, even if the line 
of fracture is at right angles, which are increased when it is 
not. 

The tensile strength per square inch of original area is more 
liable to be free from errors arising from inaccuracy than is 
that of the fractured area. But neither of these measure- 
ments provides us with a standard by which we can judge 
of the relative amount of change of form that takes place 
with different irons at the moment when they finally cease 
to resist an increase of stress ; this deficiency is supplied 
in the area at the tensile limit, which area corresponds to 
the diameter of the test-piece, at the instant when affected 
by the highest stress the material is capable of resistmg, 
and not by subsequent stress applied to a rapidly-yielding 
metal. 

Length of Test-Piece. — Not only the " percentage of elonga- 
tion " obtained by testing a piece of iron, but the strength, de- 
pends upon the length of the test-piece. Our experiments 
show, that, if an iron is judged by a test-piece whose length is 
less than four diameters, the judgment is wrong. 

Strength and Elastic Limit of Round Bar-Iron. 

In the following table the stresses by tension required to 
rupture many of the bars we have tested are arranged in their 
relative order, the greatest stress required being given prece- 
dence upon each size. 

In the columns in which the stress is reduced to the square 
inch, the areas corresponding to the actual diameters of the 
bars have been used. This gives a more correct estimate of 
the relative order of tenacity than the diameter given in the 
first column, by using which bars would frequently gain or lose 



THE BAR. 



9 



ill precedence on account of excess or lack of material, some 
being rolled " full," and others " scant." 

In the column " Standard for Size," the strength which 
we have found best adapted for cable-iron is placed for com- 
parison. 

The elastic limit as given is not from perfectly accurate data : 
it is simply the amount of stress which produced the first per- 
ceptible change of form, divided by the bar's area. 



Strength per Original Area, per Square Inch, and Elastic Limit per Square 

Inch, of 959 Round Bars. 







CO 


Strength. 


S 








CO 


Strength. 


S 






a 
o 






^ "h 


u 




o 


f-( 




•~ "^ 


















1— 1 






^ 


£^ 


a 


. 








.a 


5 M 


a 




t*- 


u 


"rt • 


o 


^ u 


i^ •!> 




«m 


u 


"rt . 


y 


^ 't 


'P o 


e 

CS 

S 


o 

a 

S3 


S 


■11 


D 
CO 


3 2 


B 

m 


a 

CS 

S 


O 

a 


01 

a 








-2 


hi. 






lbs. 


lbs. 


lbs. 


lbs. 


in. 






;6s. 


lbs. 


lbs. 


lbs. 


\ 


P 


1 


2,920 


59,885 


• • • • 




n 


N 


2 


56,200 


56,143 


32,267 


















Fx2 


3 


55,100 


55,927 


37,250 




1 


F 


4 


5,886 


54,090 


40,980 






E 
Fx3 


1 

2 


55,142 

54,800 


53,097 
54,644 


33,549 
34,695 




\ 


C 


6 


12,311 


62,700 


.... 






D 


2 


54,360 


54,687 


28,166 






C 


7 


11,699 


59,000 


.... 






A 


3 


53.997 


53,900 


26,787 






c 


8 


11,388 


57,700 


.... 






F 


3 


53,050 


53,850 


33,457 






c 


11 


10,881 


55,400 


.... 






o 


1 


50,400 


53,035 


32,410 






F 


1 


10,359 


52,275 


39,126 






F 


2 


50,300 


50.149 


35,493 




1 
















F 


5 


49,660 


52,267 


32,019 




F 


11 


16,977 


55,450 


.... 




^ 
















F 


4 


15,928 


52,050 


.... 




K 


2 


72,960 


59,461 


36,501 


65,914 




F 


11 


17,644 


57,660 


.... 






P 


2 


73,200 


56,876 


36,868 




1 
















C 


1 


71,040 


57,897 


32,469 




F 


4 


22,746 


51,546 


35,933 






D 


2 


72,300 


57,977 


31,996 




I 
















P 


2 


70,704 


55,782 


35,596 




F 


4 


30,850 


50,630 


33,931 






Px 


2 


70,250 


56,334 


33,921 




1 
















N 


2 


69,300 


56,478 


33,251 




K 


13 


48,480 


61,727 


.... 


43,665 




Fxl 


5 


68,460 


55,253 


34,784 






D 


1 


48,000 


61,115 


33,486 






D 


1 


68,160 


55,550 


28,166 






O 


1 


46,000 


57,363 


37,415 






E 


1 


67,200 


53,893 


32,712 






Fxl 


5 


45,040 


55,768 


34,729 






Fx2 


3 


66,600 


55,132 


38,603 






P 


2 


44,500 


57,807 


39,230 






Fx3 


2 


66,400 


53,247 


32,520 






A 


3 


44,126 


54,690 


34,881 






A 


3 


66,112 


53,897 


27,643 






Fx2 


3 


44,450 


56,790 


36,885 






M 


20 


65,960 


53,752 


.... 






Fx3 


2 


42,350 


53,915 


36,336 






M 


20 


65,850 


54,090 


.... 






F 


2 


41,600 


51,921 


31,300 






F 


2 


64,990 


52,970 


32,075 






D 


8 


41,547 


52,900 


.... 






F 


2 


64,700 


52,729 


39,608 






F 


5 


40,660 


52,819 


32,267 






M 


20 


64,285 


53,022 








F 


4 


40,309 


51,400 


34,600 






F 


5 


62,520 


52,620 


33.220 




H 














' 





1 


61,400 


50,040 


30,730 




K 


3 


60,096 


60,458 


37,344 


54,261 


h\ 
















D 


1 


58,700 


59,582 


33,597 




P 


94 


74,427 


54,518 


35,898 


72,133 




C 


2 


57,125 


57,470 


31,900 




If 
















Fxl 


5 


57,620 


56,434 


34,682 




M 


48 


86,862 


58,926 


37,548 


78,607 




P 


2 


56,500 


57,498 


41,311 






M 


35 


87,496 57,649 


38,578 





10 



WROUGHT-IRON AND CHAIN-CABLES. 







05 


Strength. 


o 








CD 


Strength. 


o 






o 


H 




.ti'w 


u 




c 

c 


O 
















fi 




si; 

1— 1 


tM 




^ 


a a 

.5 •"• 


a 




S-i 
h-t 


%^ 




.a 


85 


«2 


o 


N-i 


O 


H • 


S 


^ ^ 


^ o 


o 


V- 


o 


"rt . 




^2 


to 


• B 

s 


o 

V 


s 

3 


5^ 


3 
02 


•i: 3 




s 

ft 


o 
« 

S 

a 


£ 
1 


.5g 


3 
02 


O C3 
•J 3 
cc O* 

«0Q 


5 


i}i. 






lbs. 


lbs. 


lbs. 


lbs. 


in. 






lbs. 


lbs. 


lbs. 


lb8. 


1^ 


D 


1 


86,800 


58,021 


32.152 




1^ 

■^8 


Px 


2 


115,500 


54,689 


33,427 




O 


K 


2 


82,248 


55,790 


31,034 




A 


2 


111,984 


54,334 


32,163 






C 


1 


81,600 


54,949 


31,030 






D 


1 


111,360 


53,695 


30,087 






M 


28 


80,693 


54,373 


35,820 






Fx3 


2 


111,300 


53,339 


33,540 






N 


2 


81,200 


54,277 


33,622 






Fxl 


5 


110,140 


53,537 


34,335 






Fxl 


5 


80,360 


52,968 


33.275 






D 


1 


110,500 


53,614 


30,664 






Fx3 


2 


80,000 


52,733 


34,606 






J 


1 


109,400 


52,748 


.... 






E 


1 


79,296 


52,254 


25,930 






E 


1 


109,245 


52,675 


33,745 






A 


3 


78,994 


53,557 


33,650 






Fx2 


3 


108,800 


53.43S 


35,870 






P 


1 


78,624 


52,556 


30,802 






H 


1 


108,500 


52,314 


29,364 






F 


5 


78,580 


52,537 


34,469 






E 


1 


108,384 


51,946 


27,695 






F 


2 


78,300 


52,339 


39,103 






O 


1 


108,000 


52,401 


34,012 






M 


4 


78,150 


53,016 


35,379 






F 


2 


107,520 


52,163 


33,907 






Fx2 


3 


76,333 


51,487 


35,911 






G 


1 


106,200 


51,205 


33,318 






F 


2 


77,235 


51,296 


31,992 






F 


2 


105,500 


50,529 


35,390 






O 


1 


72,400 


50,594 


34,940 






F 
C 


5 
1 


105,440 
101,700 


50,970 
49,030 


33,625 
31,099 




h\ 


P 


1 


89,300 


53,345 


.... 


85,339 


m 














E 


1 


87,552 


53,944 


32,542 




K 


1 


130,000 


56,595 


38,310 


114,770 




Q 


1 


86,400 


53,238 


32,534 






B 


1 


121,150 


54,181 


.... 






B 


4 


84,862 


52,287 


32,411 






J 


1 


121,000 


54,114 


.... 






C 


1 


84,000 


51,756 


32,655 






B 


3 


118,273 


52,895 


33,145 




4 1 


J 


1 


81,800 


50,400 









E 
G 


1 
1 


116,544 
115,800 


52,120 

57,789 


35,549 
34,160 




li 


M 
K 


12 

2 


102,125 
101,280 


57,052 
57,317 


38,417 
33,412 


92,322 


If 


C 


1 


111,400 


49,821 


83,184 






D 


1 


101,200 


56,505 


32,496 




K 


1 


139,200 


57,874 


.... 


122,745 




M 


25 


99,064 


55,466 


34,780 






Px 


2 


131,900 


54,212 


33,908 






M 


26 


98,730 


55,131 


33,771 






C 


5 


130,836 


54,410 


31,354 






P 


2 


98,300 


54,159 


33,140 






P 


2 


130,050 


52,844 


33,842 






M 


17 


98,047 


54,540 


• • • • 






Fxl 


5 


129,500 


53,846 


36,573 






C 


4 


97,921 


55,404 


34,770 






H 


1 


129,400 


53,800 


27,856 






E 


1 


97,920 


55,415 


32,869 






N 


2 


129,350 


55,018 


34,283 






M 


20 


97,665 


54,816 


34,716 






D 


1 


128,600 


53,472 


31,892 






Px 


2 


97,350 


54,354 


34,617 






J 


1 


128,100 


53,264 








M 


27 


97,095 


54,095 


35,544 






D 


1 


126,720 


52,699 


27',8i7 






E 


1 


96,384 


54,544 


33,027 






Fx3 


2 


126,100 


53,154 


35,323 






P 


1 


95,904 


52,868 


29,636 






E 


1 


124,128 


51,606 


26,541 






M 


20 


95,810 


53,512 


.... 






A 


2 


123,340 


51,509 


29,404 






M 


23 


94,809 


52,941 


.... 






F 


1 


121,920 


50,690 


32,229 






Fx3 


2 


94,600 


52,819 


34,840 






G 


1 


121,200 


50,395 


36,254 






Fxl 


5 


94,520 


53,491 


34,307 






C 


1 


121,000 


50,312 


30,852 






M 


4 


93,500 


52,736 


34,901 






F 


2 


120,200 


50.547 


35,954 






N 


2 


93,400 


53,555 


34,690 






Fx2 


3 


120,1 P7 


52,314 


35,320 






C 


1 


93,100 


52,700 


35,880 






E 


1 


119,808 


49.816 


31,214 






H 


1 


92,700 


52,462 


29,992 






F 


5 


117,740 


49,738 


28,907 






D 


1 


92,160 


52,155 


27,708 






O 


1 


116,500 


50,129 


32,271 






A 


2 


91,680 


51,884 


28,794 




Ml 
















F 


2 


91,875 


51,994 


32,054 




K 


1 


148,800 


56,577 


.... 


130,965 




O 


1 


91,400 


50,919 


32,312 






B 


4 


138,507 


53,655 


.... 






F 


5 


90,925 


51,456 


34,591 






C 


1 


131,500 


50,969 


30,814 






Fx2 


3 


90,967 


51,481 


34,917 






G 


1 


129,850 


50,310 


33,565 






J 


1 


90,200 


51,047 


'. . . . 






E 


1 


129,792 


50,307 


29,767 






M 


1 


87,100 


49,292 


32,597 






J 


1 


126,300 


48,953 







If 


N 


2 


119,000 


56,344 


35,889 


107,040 


n 


K 


2 


154,080 


55,803 


.31,031 


139,430 




K 


4 


118,463 


57,132 


35,026 






C 


1 


150,336 


54,447 


32,334 






M 


10 


119.800 


57,402 


35,701 






D 


1 


149,000 


53,100 


32,074 






P 


2 


117,500 


55,634 


a3.522 






N 


1 


148,350 


54,004 


33,610 






C 


4 


116,892 


56,227 


33,207 






Fxl 


5 146,780 


52,875 


35,641 





THE BAR. 



11 









Strength. 


u 
o 










Strength. 


j3 






c 

p 








u 




o 


H 




-;-r 












S-i 




h-i 


e^ 




^ 


E^ 


a 






<» 




^ 


- ~ 


=2 


s 


O 

o 
S 




•r «^ 

5^ 


a< 


X a' 


1i 


a 

5 


o 
o 

s 


o 
o 

3 




3 














m 














OQ 






in. 






^6.S. 


Ibfs. 


».<!. 


lbs. 


in. 






/^.9. 


lbs. 


lbs. 


lbs. 


H 


Fx3 


2 


146,500 


53,361 


35,032 




2 


F 


5 


149,960 


47,569 


28,792 






P 


2 


145,200 


52,505 


32,312 






O 


2 


151,640 1 48,249 


31,413 






E 


2 


142,900 


50,880 


27,100 






D 


1 


149,800 


49,146 


33,068 






D 


1 


142,080 


51,459 


27,816 






D 


1 


142,100 


46,151 


36,050 






Px 


2 


142,000 


51,762 


32,261 




2tV 
















M 


2 


141,300 


50,363 


. • . . 




M 


1 


178,600 


51,559 


• • • • 






A 


2 


141,120 


50,584 


28,713 






M 


1 


171,200 


49,422 


. • > • 






F 


2 


140,925 


51,039 


33,067 




^ 
















Fx2 


3 


139,000 


51,159 


33,970 i 


J*t 


1 


184,600 


50,481 


« ■ • • 






F 


2 


136,600 


49,744 


35,615 






M 


1 


186,000 


51,225 


• • • . 






F 


3 


134,500 


49,355 


32,855 






A 


1 


170,784 


48,382 


30,459 






F 


2 


132,250 


48,670 


23,250 




2t\ 
















O 




129,000 


47,478 


30,842 




M 


2 


200,000 


51,666 


.... 




m 


M 




156,000 


51,707 


.... 


148,137 


n 


M 


1 


210,400 


51,530 








M 




155,300 


51,474 


.... 






M 


1 


205,800 


51.296 


.... 






M 




154,000 


51,242 


.... 






F 


3 


195,977 49,290 


32,163 




2 
















F 


2 


195,476 1 49,164 


31,966 




K 




194,880 


60,213 


31,441 


157,080 




F 


1 


192,700 1 48,898 








K 




188,160 


57,567 


30,839 






F 


1 


189,600 I 48.812 


• ■ • • 






Px 




167,900 


52,914 


31,198 






P 


2 


184,700 ! 46,866 28,241 






M 




167,600 


52,820 


• ■ ■ • 










j 






M 


-'^ 


156,000 


49,164 


.... 




-h 


F 


2 


237,930 48,475 28,932 






E 




167,712 


51,818 


27,318 






F 


3 


232,776 i 47,428 ^ 29.941 






P 


Q 


165,600 


51,684 


33,104 






F 


2 


232,400 


47,344 29,758 






P 




161,300 


50,834 


31,878 


1 
















X 




165,400 , 


52,127 


32,461 


2| 


F 


3 


275,889 


46,446 26,333 






N 




163,000 


51,370 


32,460 


I 














Fxl 




163,420 i 


52,011 


34,702 




3 


F 


3 


337,603 


47,761 26,400 






C* 




160,704 ' 


51,153 


29,335 


















D* 




160,700 


51.146 


28,567 




3i 


F 


2 


390,019 


47,014 24,591 






P 




159,840 


49,872 


29,953 


















rx2 


2 


155,500 


50,000 


36,184 




^ 


F 


2 


452,191 


47,000 24,961 


' 




Fx3 


2 


159,500 


50,763 


33,172 


















A 


9 


157,588 


50,171 


28,983 




3f 


F 


2 


515,423 


46,667 23,636 






F 


2 


152,260 


48,596 


27,634 




4 














F 


2 


151,900 


47,812 


35,864 




F 


2 


582,100 


46,322 23,430 





THE BAR.— PART II. 

Investigation- of the Effect of Differences in the 
Amount of Reduction by the Rolls. 

In procuring material upon which to make tests by tension 
both in the bar and link form, our custom was to purchase from 
manufacturers at least one bar of each size ordinarily used in 
chain-cables. Testing these bars in their normal condition by 



12 WEOUGHT-IEON AND CHAIX-CABLES. 

tension, it became evident that the strength of the different 
sizes was not in j)roportion to their areas ; but that, on the con- 
trary, there existed a variation in proportional strength which 
w^as in accord with variations in the diameter of the bars. In 
general terms it was found, that, as the diameter of the bar 
became less, the strength per square inch increased; but, in 
comparing the results obtained from a number of such sets of 
bars, it became evident that the increase of strength from be- 
tween the two extremes of, say, 2'' and 1'' was not created by 
a series of uniform steps upon each successive reduction, but 
that there was one point in the reduction where a decrease took 
the place of the usual increase, and that from this point the 
increase again began, and generally by more rapid steps. 

Thus the 2'' bar was of less strenglji than the 1|^''; the latter 
was of less than the If, which was, in turn, less than the 1|'', 
but the strength of the 1|'' was greater than that of the 1 J'' ; 
the 1|", 1^\ iy\ and sometimes the V\ being each of increased 
strength in the order given. 

We found, that, with a set of bars of the above sizes, the dif- 
ference in proportional strength between the extremes was from 
four to six thousand pounds; that the tenacity of the 1|'' ex- 
ceeded that of the 2'^ from two to three thousand pounds, and 
that'of the 1^'' from one to three thousand pounds. 

As we became fully satisfied that these variations did exist in 
all uniform irons which we examined, we considered ourselves 
justified in assuming that they would probably occur generally 
with other irons, and that, so occurring, their existence should 
be taken into consideration in any attempt to calculate the 
strength of links or other articles made from bar-iron of various 
sizes. 

Exj^eriments at the testing-machine afforded no indications 
by which we could determine any thing in regard to the causes 
of these variations. We therefore undertook to watch all the 
processes connected with the manufacture of a " set of bars," 
in hopes that while so doing we should be able to detect the 
hidden reason. 



THE BAR. 



13 



At our first visit to a rolling-mill, a set of bars were prepared 
of carefully selected material, and careful notes were taken dur- 
ing the process of manufacture, which are herewith reproduced. 

There were two bars of each size rolled. 

Notes in Regard to Manufacture of Iron F, Second Lot, 











Number op 








00 




Number of 




n 

Cu 




.2S 

a: -" 


.5 y 
o - 


Fas 


SES. 


T "^ 


o 




.2 2 


si 


Passes. 


d 












o-=s 


o 




§=3 


£ 5 


Square 


Round 


= -^ 






.S'B 


P c 


Square 


Round 


la 


Jc 




c 


E-'r3^ 


RoIIl. 


Rolls. 


m. 


CE 




ft 


^^ 


Rolls. 


Rolls. 








h.ni. 










h.ra. 






m. 


2" 


6' 


X 10" X 26" 


2.06 


15 


9 


•09 


u 


6' 


X 6" X 26" 


1.32 


13 


8 


Oblf 


2 


6 


X 10 X 26 


2.15 


15 


9 


08 


n 


6 


x6 x21 


1.00 


15 


8 


05 


1? 


6 


xlO x24 


2.02 


15 


9 


07 


n 


6 


x6 x21 


1.04 


15 


8 


04 


^ 


6 


X 10 x 24 


2.23 


15 


8 


07 


^ 


6 


X 6 x 14 


1.20 


15 


8 


04 


n 


6 


X 10 X 21 


1.40 


17 


9 


07 


n 


6 


x6 X 14 


1.20 


15 


8 


04 


Iff 


6 


X 10 X 21 


1.49 


17 


9 


06 


n 


6 


X 6 X 12 


1.10 


15 


8 


04 


6 


X 10 X 18 


1.35 


15 


9 


06 


n 


6 


X 6 X 12 


1.10 


15 


8 


04 


It 


6 


X 10 X 18 


1.40 


15 


9 


06 


1 


6 


x4 X 14 


1.10 


15 


8 


04 


^ 


6 


X 6 x26 


1.26 


13 


10 


05 


1 


6 


x4 xl4 


1.10 


15 


8 


04 



A study of these notes indicated that if there proved to ex- 
ist any marked difference in the characteristics of the different 
bars, it could not be considered as owing to want of care in 
their preparation. No accident caused delays while passing 
through the rolls, and the number of passes was quite uniform. 

By contrasting the areas of these piles with those of the 
resulting bars, it will be seen that there was a very different 
amount of reduction produced by the rolls, varying from 5.23 
to 2.76 per cent. The tenacity of these bars agreed to some 
extent with the amount of reduction, but not so closely as had 
been expected. 

The experiment was repeated by watching another set of 
bars rolled by the same mill, of the same material, the set com- 
prising bars of all sizes, ranging by ^'' from 4^' diameter to |'' 
diameter. The iron was A^ery carefully heated, and received 
a nearly uniform number of passes through the rolls. 

The dimensions of the piles, the proportion borne by the 
areas of the resultant bars, and the tensile strength and elastic 



14 



WROUGHT-IRON AND CHAIN-CABLES. 



limit per square inch of the bars, as found by tests made upon 
them entire and upon cylinders turned from the cores, are given 
in the following table. 



Iron F, Third Lot. 

Comparisons of the Reductions by the JRolls, ivith the Effects upon Tenacity and 
Elastic Limit, of Iron Fj Third Lot. 





Cm 
< 


Areaof Bar 
in percent 
of area of 
Pile. 


Tensile Strength. 


Elastic Limit. 


o 


Entire Bar. 


Core. 


Entire Bar. 


Core. 


4 

35 

31 

3^ 

3 

25 

2| 

f 
n 

1' 
l| 
11 

1 
3 

1 
4 


Sq. in. 

80 
80 
80 
80 
80 
80 
80 
72 
72 
36 
36 
36 
36 
36 
36 
23 
25 

12^ 

9 
9 
3 


Per cent. 
15.70 
13.80 
12.03 
10.37 

8.83 

7.42 

6.13 

5.52 

4.36 

7.67 

6.68 

5.76 

4.90 

4.12 

3.41 

3.96 

3.14 

4.91 

3.60 

2.50 

2.17 

3.68 

1.60 


Pounds. 

47*344 
48,505 
47,872 
49,744 
50,547 
50,529 
50,820 
52,339 
52,729 
50,149 
51,921 
50,716 
50,673 
52,297 
52,275 
54,098 
57,000 


Pounds. 
46,322 
46,667 
47,000 
47,014 
47,761 
46,466 
47,428 
49,290 
48,280 
49,370 
48,792 
49,144 
51,838 
48,819 
49,801 
50,530 
51,128 
50,374 
50,276 
51,431 
52,775 
54,108 
59,585 


Pounds. 

29,758 
31,267 
35,864 
35,615 
35,954 
35,394 
35,087 
39,103 
39,608 
35,493 
39,066 
33,931 
33,933 
34,450 
38,445 
38,475 
Lost 


Pounds. 
23,430 
23,636 
24,961 
24,591 
26,400 
26,333 
29,941 
32.163 
31,892 
37,042 
38,992 
34,208 
36,467 

40,534 
37,771 

38,596 
33,931 
35,933 
34,545 
39,126 
40,098 
Lost 



A study of the table shows first that upon the nine succes- 
sively decreasing sizes, viz., from 4'' to 2'\ there was but one ex- 
ception to a constant rise in tenacity accomjDanying the increase 
of reduction by the rolls, and that the elastic limit rose \\])o\\ 
each successive step with two exceptions, which are very slight, 
it falling off 350 pounds in one and 67 pounds in another in- 
stance ; the tenacity of the 2" (4.36 per cent of pile) being over 
that of the 4'' (15.70 per cent of pile) 1,106 pounds, and the 
elastic limit 8,462 pounds. 

From the ly (7.67 per cent of pile) to the 1|'' (3.41 per cent 
of pile), the iron was somewhat irregular, and there was but a 



THE BAR. 15 

slight rise in tenacity, viz., 431 pounds, but in the elastic limit 
the rise was 4,993 pounds. 

The tenacity of the y' (4.91 per cent of pile) was but 104 
pounds greater than that of the 1.^' (4.90 per cent of pile), that 
of the f (2.50 per cent of pile) nearly corresponding with that 
of the If (4.12 per cent of pile). 

The effect of reduction was most marked on the smaller sizes, 
the I'' (2.17 per cent of pile) having nearly 5,000 pounds less 
tenacity than the \" (1.60 per cent of pile). 

The notes taken at the mill do not indicate that either bar 
was under or over heated ; but there are indications that the 
1^'^ bar was overheated^ inasmuch as the strength of the core 
exceeded that of the entire bar. 

So far as this experiment was expected to account for the 
usually found greater strength of the 1|^' bar, it proved a fail- 
ure, for it was weaker than the bars immediately succeeding or 
preceding ; but we considered that the information gained as 
to the probable effect of under and over heating was of value. 
The indications are that if a bar is underheated it will have an 
unduly high tenacity and elastic limit, and that if overheated 
the reverse will be the case ; further, if underheated the strength 
obtained by a cylinder turned from the core will be less than 
that which would be obtained by testing the entire bar, if the 
diameter be small, and greater if the cylinder is turned from a 
large bar. 

It is possible that the above two points are interdependent, 
as the large bars are more apt to be irregularly heated than the 
small ones, and some portions of the pile must be in a state fit 
to roll before other portions are sufficiently heated ; these over- 
heated portions we turn off from the bar to produce the cylin- 
drical test-piece. 

As in the previous experiment, we believed that the thorough 
work received by all sizes put them in condition which prevent- 
ed the effect due to a slight difference in the reduction being 
plainly manifest. We therefore selected for another experiment 
the bars of a very slightly worked iron ; viz., iron N. 



16 



WROUGHT-IRON AXD CHAIN-CABLES. 



Ieon N. 

Dimensions of Piles, Areas of Piles, of Bars in percentage of Areas of Piles, 
Tenacity, Elastic Limit, ^c, of Iron N. 









Area of Bars 






Size of 
Bars. 


Dimensions of Piles. 


Area of 
Piles. 


in 

per cent of 

Area of Piles. 


Tensile 
Strength. 


Elastic 
Limit. 






Sq. In. 


Per cent. 


Pounds. 


Pounds. 


2 " 


6"x4f"x26 " 


27 


11.63 


51,848 


32,461 


1^ 


6 x4f x21 


27 


10.22 


54,034 


33,610 


If 


6 x4f x21 


27 


8.90 


55,018 


34.283 


If 


6 x4| xl6t^ 


27 


7.68 


56,344 


35,889 


^ 


4 x3| X25*' 


15 


11.78 


53,550 


34,690 


If 


4 x3f x23 


15 


9.90 


54,277 


33,622 


4 


4 x3f xl7 


15 


8.18 


56,478 


33,251 


4 


4 x3| xl6 


15 


6.62 


56,143 


32,267 



The above results supplied the missmg evidence. With one 
exception, the tenacity and elastic limit increased upon each 
successive increase in the amount of reduction by the rolls, as 
shown more plainly thus, where they are arranged in the order 
of their reduction: 1^ (6.62 per cent of pile), 56,543; Vi" 
(7.68 per cent of pile), 56,344; W (8.18 percent of pile), 
56,478 ; If" (8.90 per cent of pile), 55,018 ; W (9.90 per cent 
of pile), 54,277; 11" (10.22 per cent of pile), 54,034; 2" 
(11.63 per cent of pile), 51,848; W (11.78 per cent of pile), 
53,550. 

The tensile strength of the 2" bar was probably greater than 
recorded, the iron being so brittle that the head of the test- 
piece pulled off, and the bar could be broken by sledge-blows, 
without previous nicking. This iron, under every form of 
test, showed, by its marked contrast with iron F, the dis- 
advantages which follow too little work. 

The evidence submitted is of sufficient value to justify us 
in asserting that variations in the amount of reduction by tlie 
rolls of different bars from the same material produce fully as 
much difference in their physical characteristics as is produced 
by differences in their chemical constitution. 



THE BAE. 



17 



In order to ascertain beyond question if the rule would work- 
in both directions, and if, by giving to a series of bars a uniform 
reduction, their tenacity, &c., would prove uniform, the follow- 
ing experiment was made : — 

One of the leading manufacturers of the country, having 
placed both the facilities of his mill and as much material as 
we wished at onr service, three sets of bars were rolled, which 
are termed Fx Nos. 1, 2, and 3, all of which were of the same 
material as iron F, 

In preparing the piles for the first set, they were so graduated 
that the percentage of the pile's area borne by the bar should 
increase slightly upon each reduction in diameter of the bar ; it 
being believed that the additional work thus given to the 
smaller sizes would, in a measure, counteract the possible 
differences which might be due to overheating of the large and 
underheating of the small bars. 

The dimensions of piles, &c., are given in the following 
table, together with the tensile strength, elastic limit, &c., of 
the resultant bars. 

FxNo. 1. 

Dimensions of Piles, of Bars in per cent of Piles, Tenacity and Elastic Limit 

of Series of Bars, of Fx No. 1. 



Size 


Dimen- 


Area 


of 


sions of 


of 


Bars. 


Piles. 


Piles. 


In. 


Inches. 


Sq.In. 


2 


8x10 


80 


1^ 


8x 9 


72 


l| 


8x 8 


64 


l| 


6x10 


60 


4 


6x 9 


54 


If 


6x 8 


48 


H 


6x 8 


48 


4 


6x 6 


36 


1 


6x 5 


30 



Area of Bars 

in 
per cent 

of 
Area of Piles, 



Per cent. 

3.93 
3.83 
3.75 
3.45 
3.27 
3.09 

2.55 
2.76 

2.62 



Tensile 


Elastic 


Strength. 


Limit. 


Pounds. 


Pounds. 


52,011 


34,702 


52,874 


35,641 


53,846 


36,573 


53,537 


34,235 


53,491 


34,307 


52,968 


33,275 


55,307 


34,784 


56,434 


34,682 


55,770 


34,279 



Average 53,121 T. S. and 
34,700 E. L. 



Average 55,837 T. S. 
34,582 E. L. 



and 



18 



TVKOUGHT-IKON AND CHAIN-CABLES. 



The results show a nearly uniform tenacity for the first six 
sizes, then an increase, which remains quite uniform for the 
other three, the elastic limit remaining very uniform tlirough- 
out. 

The tenacity of the 2'' bar, rolled by the usual process (iron 
F, 2''), its area being 5.23 per cent of pile, was 47,569 pounds, 
showing an increase upon this size, by the experimental pro- 
cess, of 4,442 pounds ; and the increase of the elastic limit, 
5,910 pounds, was still more marked. 

No explanation, except that they were possibly not enough 
heated, accounts for the increased tenacity of the IJ'' and the 
r' bars; and the li^'was, by mistake, rolled from too large a 
pile. 

A second attempt to produce a set of bars of uniform 
tenacity resulted in a complete failure, due, we were assured, 
to a misunderstanding in regard to heating the piles ; but on a 
third attempt we were successful, as shown by the following 
table, in which the usual data are given : — 

Dimensions and Areas of Piles, Areas of Bars in percentages of Piles, Tensile 
Strength, Elastic Limit, Sfc, of Nine Bars of Iron Fx No. 3. 









Area of Bars 






Size of 


Dimensions 


Area of 


in 


Tensile 


Elastic 


Bars. 


of Piles. 


Piles. 


per cent of 
Area of Piles. 


Strength. 


Limit. 


Inches. 


Inches. 


Sq.In. 


Per cent. 


Pounds. 


Pounds. 


2 


8x10 


80 


3.92 


50,763 


33,258 


1^ 


8x10 


80 


3.45 


53,361 


35,032 


If 


8x 9 


72 


3.34 


53,154 


35,323 


n 


8x 8 


64 


3.24 


53,329 


33,520 


u 


6x 9 


54 


3.27 


52,819 


34,840 


If 


6x 7 


42 


3.53 


52,733 


34,606 


11 


6x 6 


36 


3.41 


53,248 


33,520 


H 


6x 5 


30 


3.31 


54,648 


34,695 


1 


5x 5 


25 


3.14 


53,915 


36,287 



The pile for the 2" was necessarily two small, as there were 
no rolls in the mills which would take a larger pile. The 
record is, however, of value as a contrast to that of the other 



THE BAE. 19 

eight bars, the average of whose tensile strength, 53,401 pounds, 
and of the elastic limit, 34,365 pounds, is but slightly varied 
from by any of the bars. 

Two practical results of value may be deduced from this 
investigation of the action of the rolls. 

The first is, that, as important differences exist in the pro- 
portionate strength of different-sized bars made of the same 
material, which are due entirely to differences in the processes 
by which they are manufactured, and as the elimination or 
reduction of such differences would necessitate such a great 
and expensive change in the system by which the bars are pro- 
duced that it is not probable that it will be often attempted, 
it is necessary that these differences should be taken into 
consideration when estimates of the strength of any structure 
in which rolled wrought-iron, of different sizes, is introduced, 
are made, and in all tables of strength based upon the strength 
of such bars. 

Second, that, where the increased value of the bars will 
justify the increased expense of their production, those of ^' 
diameter can be increased in tensile strength over 15,000 
pounds ; and it is not improbable that bars of ^' diameter can 
have the strength increased over 60,000 pounds, with no loss 
in their power to resist sudden strains. 



20 WROUGHT-IKON AND CHAIN-CABLES. 



SECTIOISr II. 

Part I. — A Paper showing, hy many Experiments, the Correct Form and Pro- 
jjoriion of Test-Pieces to be used in order to procure correctly the Tenacity, 
Elastic Limit, S^^c, of Various Metals. Part II. — A Comparison of the 
Strength of Bars in their Normal Condition, ivith the same after the Bars have 
been reduced hy turning away the Surface. 

PART L— FORM AXD PROPORTIONS OF TEST-PIECES. 

In obtaining the results introduced in the tables of records 
of bars tested by tension, we have used the two testing-ma- 
chines A and B. 

By the first, we have tested all the bars of diameter greater 
than one inch ; and, by the latter, bars in their normal condition 
of less than one inch diameter, and cylinders turned from tlie 
larger bars. 

Our tests made upon these cylinders gave results of tensile 
strength and elastic limit which were so much lower than the 
manufacturers of the various irons considered their products 
equal to, that some dissatisfaction and doubt as to their cor- 
rectness were expressed. 

Upon examination, we found that in nearly all cases where 
our results were supposed to be erroneous,- — on account of a 
lack of coincidence with results obtained in some cases by the 
experiments of private testers of iron, and in others by tests 
made in government navy-yards, by persons presumed to be 
competent, — the tests whose results cast doubt upon ours had 
been made upon test-pieces turned from the bars to a reduced 
diameter, which at one point was reduced by a groove to a 
much less one, as shown in Fig. 1, p. 25. 



FORM AND PEOPORTIOXS OF TEST-PIECES. 



21 



The errors which arise through the use of this erroneously 
shaped and proportioned test-piece have been frequently pointed 
out, first by Kirkaldy, and subsequently by C. B. Richards, mem- 
ber American Society of Civil Engineers ; but it does not ap- 
pear that even yet the errors which thus arise are fully recog- 
nized. As a case in point, the following comparisons of the 
strength of various-sized bars of iron F, as found by our tests, 
and as furnished to the manufacturers by so-called testers, 
will fully illustrate. 

This iron is ahcays of so uniform a strength and quality, that 
the test of one bar furnishes most valuable evidence as to the 
probable strength of another. 

Strength per Square Inch of Iron F, as found hy and as furnished to the 

Coynmittee. 



Size. 


33 
H 

K 

C 

d 


Strength Found. 


02 
H 

6 


Strength Furnished. 




OS 

o 

o 
C 


From — 


To — 


Average 


From — 


To — 


Average 


k3 
«2 


Of 

2f 
21 

l^ 

1| 

If 
1^ 

i| 

If 




3 
3 

3 

9 

8 
8 
8 
8 
8 


Pounds. 

46,164 

47,558 

49,i55 

46,862 
48,370 
48,792 
49,144 
49,342 
48,819 


Pounds. 

46,702 
47,871 

49,465 

49.700 
51,300 
50,342 
51,300 
51,840 
50,000 


Pounds. 

46,446 
47,764 

49,623 

48,i32 
49,048 
50,325 
51,221 
51,423 
52,396 


5 
4 
8 
18 
15 
15 
12 

i2 


Pounds. 

58.434 
54,759 
50,773 
58,111 
57,473 
59,440 
57,999 

63,ii6 

66,3i2 


Pounds. 

65,357 
60.757 
64,099 
71,025 
64,823 
67,471 
66,907 

75,545 

68,255 


Pounds. 

62.540 
57,230 
59,048 
63,586 
63,300 
63,350 
63,230 

65,083 

67,062 


16,094 
9,472 

13,963 

15,2i8 



"With the tabulated statement furnished, the average tensile 
strength of all sizes combined was given at 63,207 pounds ; and 
the results from the sizes If and If'' had been consolidated, 
also those from \^' and \\" . 

With experimenters developing by accident such a uni- 
formity in the average tensile strength of the various sizes, it 
is not to be wondered at that no attention had been drawn to 



22 



WROUGHT-IEON AND CHAIN-CABLES. 



the variation in strength accompanying variations in diameter, 
which is i^lainly indicated in our more correctly-made experi- 
ments. 

The broken test-pieces by which the results were procured 
were shown to us, and they were of the groove-form. 

We determined to thoroughly investigate the effect upon the 
results which were due to variations in the proportions of the 
test-pieces. The stock of contract-chain on hand, all of which 
had been considered to be of a tensile strength of at least 
60,000 pounds per square inch (the standard at that time, as it 
is, or was, also, of the British navy), furnished material for 
experiment ; and a number of comparative tests were made by 
means of grooved test-pieces and short cylinders, with results 
as follows : — 



Comparison of Results obtained from Chain-Iron on Jiand, hy means of Grooved 
Test-Pieces and Short Turned Cylinders. 





Dimensions of 
Test-Piece. 


jSTo. of 
Tests. 


Tensile Strength 
PER Square Incu. 


Grooves ex- 
ceed Cylin- 
ders BY — 






9 
< 


■i 


CI 

.S 
">> 


> 

O 
O 

o 

3 
2 
2 
2 
2 
2 
1 

2 

2 

2 


CO 

o 


CO 

o 
> 
O 

2 
o 


CO 

C 
O 


o 


Appearance op 
Fracture. 


In. 
1 

1t\ 

'A 

If 
If 
h\ 
We 

H 

1^ 

If 


Square Inch. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-quarter. 
One-half. 
One-half. 
One-half. 
One-half. 
One-half. 
One-half. 


In. 

1.20 
1.20 
1.20 
1.20 
1.20 
1.20 
1.20 
1.20 
1.20 
1.20 
1.25 
1.25 
1.25 
1.25 
1.25 
1.25 


3 

2 
3 
2 

2 
2 
2 

1 
2 
2 
2 
2 
2 
2 



2 


Pounds. 

57,700 
50,000 
52,000 
48,000 
58,900 
52,400 
54,200 
58,400 
40,900 
55,450 
54,300 
58,400 
51,500 
50,900 
44,000 
48,200 


Pounds. 

71,530 
70,000 
05,850 
59,000 
07,400 
02,800 
07,200 
07,200 
54,500 
05,400 
00,000 
09,700 
04,900 
02,400 
58,500 
56,900 


13,830 

14,000 

13,190 

11,000 

8,500 

10,400 

13,000 

8,800 

7,600 

9,950 

11,700 

11,300 

13,400 

11,500 

9,500 

8,700 


23.5 

24.5 

24.0 

25.0 

14.6 

20.0 

24.0 

15.0 

16.0 

18.0 

21.0 

19.0 

26. 

22. 

19! 

18. 


Fine steely. 
Fine steely. 
Fine steely. 
Fine steely. 
Coarse granulous. 
Fibrous. 
Fibrous. 
Coarse fibre. 
Coarse granulous. 
Gray fibre. 
Gray fibre. 
Gray fibre. 
Coarse granulous. 
Coarse granulous. 
Coarse granulous. 
Coarse granulous. 



rOEM AND PROPORTIONS OF TEST-PIECES. 



23 



These results made it evident that the government had not 
received iron of such great tensile strength as was supposed ; 
and this was made more certain by the results procured subse- 
quently by comparative tests upon several of the irons which 
make up our records. These are here given. One groove-test 
was made upon each size. 



Comparison of Results obtained from CijUndrical and from Grooved Test-Pieces. 

Irons C, B, J, F, L, E. 



Iron. 


Dimensions 
OF Test- 
Piece. 


T. 
W 

W 

H 
o 
c 


Ultimate 
Strength per 
Square Inch. 


Grooves ex- 
ceed Cylin- 
ders BY — 




1 


^ Cm 




.a 

s 
o 


O 


5 


c 

3 
O 


c 
o 
O 

Pi 


Remarks. 


c 
c 
c 
c 
c 

B 
B 
J 
J 
F 
F 
L 
L 
L 
L 
L 
E 
E 


In. 
■ 5 

if 

!!• 

k' 
If . 

1 
If 

11 




In. 

.804 
.804 
.504 
.504 
.504 
.800 
.800 
.800 
.040 
.800 
.504 
.800 
.504 
.070 

.800 
.504 


In. 

1.25 
1.20 
1.30 
1.20 
1.25 
1.30 
1.30 
1.30 
1.40 
1.20 
1.30 
1.35 
1.37 
1.35 

V.30 
1.30 


2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
2 
1 
2 
2 
2 


Pounds. 

54,800 
57,700 
58,900 
58,300 
59,100 
07,000 
05,050 
57,300 
02,200 
01,900 
00,520 
75,250 
74,400 
94,400 

80',600 
59,520 
01,000 


Pounds. 

47,885 
48,000 
50,000 
52,000 
45,800 
51,900 
53,000 
50,350 
50,300 
50,130 
50,400 
58,390 
.59,290 
75,233 
74,000 
00,500 
50,080 
50,000 


6,915 

9,100 

2,900 

6,300 

13,300 

15,100 

12,050 

6,950 

11,900 

11,770 

10,120 

16,860 

15,110 

19,167 

13,500 

9,440 

11,060 


14.5 
10.8 

5 
12.1 
20 
29 
22.5 
14 
24 
23.5 
20 
29 
25 
25 
26.5 
20 
18 
21 


Strong and tough. 

Hard and coarse. 

Hard and coarse. 

Hard and coarse. 

Strong and tough. 

Strong, good stock. 

Not enough work. 

Irregular. 

Irregular. 

Soft and ductile. 

Soft and ductile. 

Steel. 

Steel. 

Steel. 

Steel . 

Steel. 

Tough and strong. 

Tough and strong. 



It is to be noticed that the difference between the results 
obtained by the two methods is greater in pure refined iron 
than it is in coarse material. A single experiment, made with 
a test-piece of each form upon cast-iron, confirmed this view : 
tlie difference of results was less than one per cent, and the 
cylinder proved that much the stronger. 



24 



WROUGHT-IEOX AND CHAIX-CABLES. 



A series of experiments was undertaken for the express pur- 
pose of enabling us to decide upon the correct form and 
proportions necessary in the test-pieces to insure correct results. 
The first of this series Avas made upon eighteen test-pieces 
turned from a 2'' bar of a remarkably pure, refined, and uniform 
iron (K). 

No. 1 of this series was 10'' long ; and the length decreased 
upon each successive number, until, at 18, the groove-form was 
reached. The diameters were nearly constant, except in two 
cases where seams encountered made it necessary to turn away 
more iron. The results are given in the following table : — 

Iron K. 











Stress per 






Number. 


Original 
Length. 


Per Cent of 
Elongation. 


Per Cent of 
Contraction 


Square Inch 
when Piece 


Breaking 
Stress per 


Remarks. 








of Area. 


began to 


Square Inch. 












Stretch. 








Inches. 






Pounds. 


Pounds. 




1 


10 


23.1 


38.2 


29,678 


54,888 


Slight seam. 




9^ 


24 3 


36.5 


28,011 


55,288 




3 


9 


21.5 


31.1 


29,345 


55,355 




4 


2^ 


22 


31.2 


29,315 


55,622 




5 
6 


Ik 


25 


39.9 


30,840 


54,890 


Slight seam. 


t 


25.8 


38.6 


30,412 


55,488 




7 


H 


22.1 


40.0 


28,562 


51.800 


Bad seam. 


8 


6 


22.3 


34.7 


30,600 


55.418 




9 


52 


25.4 


39.3 


29,475 


55,333 




10 
11 


O 

4 


21.2 
25 7 


32.2 
37.*4 


29,278 
29,705 


55,887 
55,532 


Slight seam. 


12 


l^ 


26.7 


36.6 


31,817 


55,482 




13 


3 


27 


38.3 


31,123 


56,190 




14 
15 

16 
17 


9 


27 


36.2 


33,428 


56,428 


Seamy. 


1* 


26 
37 


34.0 
34.3 


42,249 

34,288 


57,096 
58,933 


Seamy. 


„ 4 


30 


37.0 


57,565 


59,388 


Seamy. 


18 


Groove. 




20.6 


45,442 


71,300 



Nos. 13 and 18 of the preceding table are reproduced in the 
following illustration : — 

Fig. 1 being Xo. 18 of the table, and Fig. 2 No. 13 ; 
In Fig. 1, the length a h was 3'', the diameter, c c, .976''. 
In Fig. 2, the length a h was 3", the diameter, c c, .970 



Tiff 



FORM AXD PROPORTIOXS OF TEST-PIECES. 



25 



The pieces were nearly the same in dimensions; yet the stress 
at whicli No. 13 broke, reduced to the square inch, was over 
fifteen thousand pounds less than that required to break No. 18. 
This difference would be very great in estimating the entire 
strength of the bar from the results of the two pieces. Were 
those from No. 18 correct, the bar would be equal to a strain 
of one hundred tons; while No. 13 shows that less than 
seventy-nine tons w^ould 
tear it asunder. 

By the table, we see 
that the piece No. 13 
gave higher results than 
those w^hich were long- 
er; the average tensile 
strength developed by 
Nos. 2, 3, 4, 6, 9, 10, 
11, and 12 being bb^- 
488 pounds per square 
inch, while No. 13 gives 
56,190 pounds, — an ex- 
cess of 751 pounds, — 
thus suggesting that the 
length of this piece, viz., 
three inches, was not sufficient to insure correct results. 

No. 12 gives a result much closer to the averages, as do Nos. 
11 and 10. 

Assuming that the proper length should be a certain percent- 
age of the diameter, we find No. 13, which is less than four 
diameters in length, is not long enough ; No. 12, of about four 
diameters, gives correct results. 

The preceding tests in this investigation having been made 
upon iron with considerable tensile strength, it was thought 
advisable to make one more experiment with a bar of xqvj soft 
and ductile iron. I 

A two-inch bar was selected, which, although 'of low tensile 
strength, was very tough and ductile. 




, 


fl 




<v 


4e 







I 




^ 


1 






Fig. 1, No. 18, Table. 



Fig. 2, No. 13, Table. 



26 



WKOUGHT-IKON AND CHAIN-CABLES. 



From this nine test-pieces were turned, of lengths from 
eight inches clown, to the groove-form, each successive piece 
being nearly one inch shorter than its predecessor, and all 
being nearly of uniform diameter. They were tested with the 



following results : — 



Iron D. 



No. 


Diameter. 


Original 
Length. 


Reduction 
OF Area. 


Per Cent 
Elonga- 
tion. 


First 

Stretch 

PER Square 

Inch. 


Ultimate 

Stress per 

Square Inch. 


Original. 


Fractured. 


1 

2 
3 

4 
5 
6 
7 
8 
9 


Inches. 

1.000 

.999 

1.000 

.999 

.998 

1.000 

1.001 

1.000 

.985 


Inches. 

.693 
.675 
.704 
.700 

.683 
.705 
.700 
.718 
.897 


Inches. 
8 

5.82 
4.90 
3.95 
2.98 
1.98 
.975 
Groove. 


Per Cent. 
52 
54.3 
50.3 
50.9 
53.1 
50.3 
51 
48.4 
17 


28 

29.8 

29.9 

31 

35 

36.1 

40.4 

45.2 


Pounds. 
28,619 
30,000 
26.700 
28,060 
26,588 

28,666 

28,200 
48,000 


Pounds. 

45.800 
45.930 
45.995 
45,768 
46,561 
46,759 
46.734 
47,033 
61,023 



The results indicate that with iron of this character a lenofth 
equal to four diameters is not quite sufficient to insure accurate 
results. 

No. 5, which was nearly four diameters in length, gave a 
tensile strength greater by 689 pounds per square inch than 
was developed by Nos. 1, 2, 3, and 4, which were very uniform ; 
No. 4 being five diameters in length, and long enougli. No. 6, of 
three diameters, gave still higher results ; and when the groove- 
form was reached there was a sudden rise of over 13,000 pounds, 
a difference equal to 33 per cent of the actual strength. 

In conclusion, our results lead us to the decision, that, in 
testing iron, no test-piece should be less than one-half inch in 
diameter, as inaccuracy is more probable with a small than with 
a large piece, and the errors are more increased by reduction 
to the square inch ; that the length should not be less than 
four times the diameter in any case ; and that, with soft ductile 
metal, five or six diameters would be preferable. 



COMPARATIVE STEENGTH OF EOUGH AND TUENED BAES. 27 

These rules hold good in testing steel also, according to a 
number of results, which have been submitted to the commit- 
tee, of tests made upon American Bessemer rail steel; which 
results are confirmed by those obtained by Col. Wilmot at the 
Woolwich Arsenal, made also upon Bessemer steel, which we 
quote as follows : — 

Material, Bessemer steel ; test-pieces of one square inch area. 

TENSILE STRENGTH. POUNDS PER SQUARE INCH. 

By groove form : Highest 162,974 

Lowest 136,490 

Average 153,677 

By cylinder: Highest 123,165 

Lowest 103,255 

Average 114,460 

The grooved thus exceeding the cylinder form, 32 to 34 per 
cent. 

PART IL — COMPARATIVE STRENGTH OF BARS IX THEIR 
NORMAL CONDITION, AND AS REDUCED BY TURNING 
AWAY THE SKIN AND ADJACENT IRON. 

A few tests were made by tension ; for the double purpose of 
ascertaining if the strength per square inch of iron bars with 
or without the skin is the same, and to compare the results 
obtained by the two testing-machines A and B. The following 
tables show some of the results ; — 



28 



WEOUGHT-IEOX AXD CHAIX-CABLES. 



Consolidation of Results from 226 Tests hy Tension upon Test-Pieces^ with and 
icithout Skin, showing Preponderance of Strength in Favor of the Bar in 
Normal Condition. 



TESTIXG-MACHINE A. 





PS 

< 


No. or 
Tests. 


Tensile Strength per 
Square Inch. 


Excess or 


Strength. 


Iron. 


o 


















o 


o 

c 


Rough. 


Turned. 


Rough over 
Turned. 


Turned over 
Rough. 




Inches. 






Pounds. 


Pounds. 


Pounds. 


Pounds. 


D . . . . 


If 






51,499 


51,895 


.... 


396 


D . 






l| 






51,127 


50,383 


744 


.... 


D . 






4 






52,156 


53,347 


. • . . 


1,191 


D . 






i| 






51 


275 


51,271 


4 


.... 


C . 






2* 






49 


678 


49,735 


33 


. . . ^ 


C . 






n 






49 


095 


48,726 


369 


.... 


C . 






16 






49 


512 


51,367 


145 


.... 


C . 






If 






51 


233 


49,419 


1,814 


.... 


E . 






l| 






51 


739 


49,044 


2,695 


.... 


E . 






If 






51 


606 


51,740 


.... 


134 


E . 






l| 






51 


944 


50,844 


1,100 


.... 


E . 






H 






55 


411 


55,409 


2 


.... 


E . 






i| 






52 


255 


51,843 


412 


.... 


E . 






4 






53 


894 


53,309 


585 


.... 


E . 






4 






53 


098 


53,497 


.... 


399 


Hammered . 


4 






52 


570 


52,424 


146 


.... 


Hammered . 


4 






56 


818 


54,143 


2,675 


.... 


Hammered . 


4 


2 




57 


280 


55,021 


2,259 




Hammered . 


4 


1 




55 


542 


55,805 


.... 


263 


F . . . . 


i' 


5 




52 


819 


52,810 


9 


.... 


F 








H 


5 




52 


267 


51,675 


592 


.... 


F 








4 


5 




52 


620 


51,949 


671 


.... 


F 








4 


5 




52 


537 


50,403 


2,134 


.... 


F 








i 


5 




51 


456 


50,799 


657 


.... 


F 








5 




50 


970 


49,605 


1,365 


.... 


F 








% 


5 




49 


738 


50,201 


.... 


463 


F 








5 




49 


061 


49,682 




621 


F 








2 


5 




47 


569 


48,170 


.... 


601 


F 








01 

" 4 


2 


2 


48 


505 


49,164 


.... 


659 


F 








■4 


2 


2 


47 


344 


48,475 


.... 


1,131 






69 


33 











COMPAEATIYE STEEXGTH OF EOUGH AND TURNED BAES. 29 



TESTING-MACHINE B. 





< 
P. 


No. OF 

Tests. 


Tensile Strength per 
Square Inch. 


Excess of 


Strength. 


Iron. 


o 




^ 














"5) 
1 


o 

c 


Rough. 


Turned. 


Rough over 
Turned. 


Turned over 
Rough. 




Inches. 






rounds. 


Pounds. 


Pounds. 


Pounds. 


c . . 


. . 11 


4 


3 


52,949 


52,796 


153 




c . 




. 1 


3 


3 


54,076 


52,475 


1,601 


.... 


c . 




1 
• '2 


G 


5 


55,725 


55,311 


414 


.... 


c . 






8 


G 


57,84G 


62,813 


• . . . 


4,967 


D . 




. 1 


6 


4 


53,400 


52,408 


992 


.... 


K . 




. 1 


3 


3 


62,2G9 


60,536 


1,733 


• • . . 


K . 




. 1 


4 


3 


61,945 


62,156 


.... 


211 


Contract i 


ron, J 


3 


4 


60,466 


59,696 


770 




P, first lot 


4 


4 


52,155 


51,547 


608 


.... 


F, first lot 


. 1 


3 


3 


52,645 


51,540 


1,105 


.... 


F, first lot 


• I 


6 


5 


57,257 


57,668 




411 


F, first lot 


6 

• 8 


6 


5 


55,644 


54,964 


680 


.... 


F, third k 


)t . 1 


3 




50,71G 


50,374 


342 


.... 




f 


3 




51,969 


50,276 


693 


.... 




o. 


3 




52,032 


51,431 


601 


.... 




3 


3 




53,755 


52,775 


980 


.... 




' 


3 
71 


53 











In case of the half-inch bars of iron C, of which the turned so 
greatly exceeded the rough in strength, there is some reason to 
suspect that a piece of the bar of iron K was by mistake sub- 
stituted for that of C. In case of iron K, where the turned 
exceeded the rough bar, the threads of the latter stripped. 

The accumulated evidence indicates that the strength of the 
skin of the bar is greater in proportion to its area than that of 
the rest of the bar. 

In making the foregoing tests, we find that in sixteen com- 
parative tests of small bars by testing-machine B, and in thirty 
comparative tests upon larger bars by testing-machine A, mak- 
ing forty-six in all, in thirteen cases of the former and twenty 
of the latter, thirty-three, or over 72 per cent, the excess of 
streno:th occurred with bars in their normal condition. 



30 WROUGHT-IEON AND CHAIN-CABLES. 

With iron F, which was so uniform in its structure that any 
peculiarity which manifested itself by any particular test seemed 
to indicate a possible law, we find that, with the bars which 
received the most work, viz., from 1" to 1|'' inclusive, the rough 
bars were stronger than the turned; above l|''the more slightly- 
worked sizes reversed the proportion. If this result can be 
accepted as indicative, it would be wise, in estimating the entire 
strength of a large bar by the data afforded by the test of a 
cylinder turned from its centre, to, as has already been said, 
consider it probable that an over-estimate would be made. For 
instance, the strength of the 2J'' bar was 192,861 pounds by 
actual test of the entire bar ; by test of turned bar, 195,481 
pounds; by test of cylinder, 195,981 pounds; showing a possible 
over-estimate of 3,120 pounds by use of cylinder turned from 
the core. 



TESTS OF BAES BY IMPACT. 31 



SECTION III. 

Tests of Bars hy Impact; showing Action of Various Types of Iron under 

Sudden Strains. 

The tests by which we have ascertained the powers of the 
various irons of the series to resist steady tensional strains, 
applied in the direction of the fibre, and when manufactured 
into Knks, have furnished us with no data by which their rela- 
tive powers to resist sudden strains, applied transversely, could 
be judged. As cables are more frequently broken by strains 
of this nature than by all other causes combined, it was con- 
sidered to be absolutely necessary that the series should be 
subjected to such tests as would develop their relative values 
in this respect before we could express an opinion as to which 
of the varying characteristics, as developed by tension alone, 
indicated that the iron in which they existed could be con- 
sidered as in every way suitable for the manufacture of 
cables. 

Having no apparatus by which such tests could be made, 
one was devised by the chairman of the committee, by the 
use of which we were enabled to form a fair judgment as 
to the comparative values of the irons when subjected to 
shocks. 

The following is a description of this machine, which was 
known as the " impact hammer : " — 

The Impact Hammer. — A cast-iron hammer having a wedge- 
shaped impa<3t surface upon its lower side is made to transverse 
two perpendicular iron rods of say 2|- inches diameter and from 



32 -WEOUGHT-IRON AND CHALK-CABLES. 

SO to 50 feet in lengtli, which pass tiirough holes in the body 
of the hammer. The hammer may be of any weight, a con- 
venient one being 100 pounds. A traveller of wood or metal, 
fitted with a pair of hooks which can be opened or closed by 
pulling lip a cord attached to them, is placed upon the rods 
above the hammer. At the foot of the rods, they passing 
through it, is fitted a cast-iron block with a cylindrical opening 
eight inches in diameter. The specimen of iron to be tested 
is placed across this circular hole, the hammer resting upon the 
box which surrounds the anvil and supported by a chock, to 
prevent accidents. A common purchase, through which a hoist- 
ing-rope is led to the windlass, is secured to the portion of the 
framework. At the side of one of the rods an upright, marked 
plainly in feet and inches, is secured. 

To use the machine, the hammer is hoisted to the desired 
height, the lower edge of the hammer being brought in line 
with the figure on the measuring-rod. When at the proper 
height, the tripping-line is pulled, opening the hooks, and re- 
leasing the hammer, which falls, striking the specimen in the 
centre a blow whose force can be measured, and which is de- 
pendent upon the force of gravity at the location, and slightly 
diminished by friction. 

Method of testing by Impact. 

Our method of testing by this machine was this : Test-j)ieces, 
not less than tAvelve diameters in length, were placed across 
the hole through the anvil, the centres being directly under the 
edge of the wedge-shaped hammer, which was raised to various 
heights, and allowed to drop upon them. 

Bars of some irons which were tested by this method could, 
while in their normal condition, the skin being in no manner 
nicked or weakened, be broken by two blows of less than three 
thousand foot-pounds force ; with other irons it was necessary 
to weaken them by a circular score 3^ of an inch deep, that 
we might succeed in breaking the test-piece, it not being con- 
venient to use a hammer over one hundred pounds weight. 



QQ 



TESTS OF BAES BY BIPACT. 66 

which could be hoisted but thirty feet. This cut through the 
skin reduced the bar's power to resist, in the same manner that 
it is reduced by the ordinary method of nicking witli a cold- 
chisel, and the blows of the hammer were of the same nature 
as those given by sledge-hammers ; but with this machine the 
force of the blow could be regulated and known, and the 
weakening produced by the cuts made uniform. 

The wedge-shaped portion of the hammer permitted a bar to 
bend to an angle of 120.° 

Through the data collected by the test, by this method, 
of a large number of bars of varipus irons differing widely in 
character, we were able to detect the existence of a connecting 
link, and partially trace its course, between the characteristics 
displayed under tension, and those produced by impact. 

Iron with high tensile strength generally proved to be pos- 
sessed of but comparatively low resilience ; it would break 
under the blows with but slight deflection, and leave a fractured 
surface, smooth as though the bar had been cut in two by a 
sharp knife, the ends of the fibres showing, like steel, a fine, 
slightly granulous surface. 

Iron of coarse, slightly-worked character would have an 
equally smooth and bright surface, but the coarse, granulous 
appearance of the cut fibres denoted how slightly they had 
been affected by the rolls. 

Iron with a high elastic limit would resist the first blow, with 
but little injury or deflection; but, the deflection once started 
by subsequent blows, it would yield more at each than would 
other irons with a lower limit, which were more affected by the 
first blow. Some irons would, after having been weakened by 
the circular cut through the skin, resist, with slight injury, 
blows which would break in two bars of the same size of other 
irons which had not been so weakened. 

There are many irons, valuable for many purposes, which 
would not yield good results under this form of test ; but, 
however valuable for other purposes, the material which proves 
brittle under test cannot be expected, when made into cable, 



34 WEOUGHT-IEON AXD CHAIN-CABLES. 

and subjected to strains of a similar nature, to prove equal to 
its tasks. 

Iron which is materially weakened by a repetition of slight, 
sudden strains, none of which produce perceptible injury, but 
which do so injure it that eventually a strain no greater, and 
perhaps much less, than those previously encountered, will 
destroy it, is not suitable for cable. Iron whose entire strength 
depends upon its remaining perfectly free from abrasion, or 
slight cracks, is not suitable for cables. Our tests by impact 
revealed that large quantities of iron possessing the above 
defects had been accumulated by the government, all having 
passed satisfactorily the examinations, which consisted of 
tension tests made upon test-pieces of erroneous proportions. 
Much of this iron was of good material ; but the low price at 
which it had to be supplied, in order that the lowest bidder 
should, as the law directed, receive the contract, had neces- 
sitated, that, in order to make it cheap enough, but very little 
work should be expended upon it. 

Our experiments demonstrated not only its want of value in 
its present state, but also that by thorough work it could be 
vastly improved ; and when, in addition to this work, material 
of no greater cost, but possessing qualities that the coarse 
chain-iron lacked, was added, we found that most valuable 
iron, capable of resisting all strains, was produced. 

An example of such a transformation will be described: 
The material selected was taken from the pile of 2-^^" chain- 
iron, and was probably as inferior a bar of iron as could be 
found in the pile, or in our markets, there being in the stock of 
chain-iron, however, a great many equally poor. 

These bolts, each over 26'' long, were thoroughly tested. 
Several which had not been weakened by a score were broken 
square in two by a single blow of the hammer dropped twenty- 
five to thirty feet; others, having been struck from ten to 
twenty times by the hannner, from a height of eight or ten 
feet, and showing no injury or deflection, would, upon receiving 
another blow of no greater force, break in two; other bars, 



TESTS OF BARS BY IMPACT. 35 

scored as has been described, would break in two at single 
blows of from one to three feet drop. 

In all cases, the appearance of the fracture was the same, 
and would be described as " bright, coarse, granulous." 

Iron from this lot, having been first thoroughly re-worked, 
was piled with alternate layers of old hoiler-iy^on^ and hammered 
into a bloom, from which a bar of 2'' diameter was swaged. 
This was cut into pieces 2-i'' long, and the pieces were scored 
in two places, 8'' apart, and then tested as was the original 
bar, except that each drop of the hammer was from a height 
of thirty feet. The first score received ten such blows before it 
was entirely torn in two, and the fractured surface appeared 
fibrous. ^ 

The extreme difference between the appearance of fractures 
made upon the same material (and it of great resisting powers), 
by different degrees of the same force, indicates that it is unsafe, 
even for an expert, to attempt to give evidence as to the char- 
acter of the material from which a bridge, axle, or cable, that 
has been accidentally broken, was made, unless he knows just 
how it was broken. To render a judgment upon this point, a 
person must not only be an expert, but he must know by what 
character and amount of force the fracture was produced." 

The fractures illustrated in the frontispiece, Fig. 2, supply 
evidence of this fact. The three were made by impact upon 
the same bar (of iron A, 1^'' diameter) which was scored in 
three places, eight inches apart. At a the score was slight, and 
the piece was torn in two by repeated light blows. 

At h the score was the same ; but, after the bar had been 
broken half in two by light blows, one heavy one was given, 
which cut in two the remainder. 

At c the score was deep, and one heavy blow did the work : 
a would be described as " all fibrous," h as " half granulous and 
half fibi^pus," c as " bright granulous." 

Irons F, Fx, O, D, H, G, Px, and some of the bars of B, C, 
and P, resemble more or less in their characteristics the iron 
shown in this plate. 



36 WEOUGHT-IEOX AND CHAIN-CABLES. 

Baeking. 

A peculiar phenomenon occurred with irons of a certain type, 
during the test by impact, which was given the shop -name of 
"barking." The illustration in frontispiece, Fig. 1, will give 
a clearer idea than description can of this phenomenon. This 
occurred only in tests of very tough, ductile iron which had been 
thoroughly worked, and which required several repetitions of 
the blows to break in two. 

As the deflection caused by each successive blow increased, 
the transverse crack at the lower part of the test-piece widened, 
and the surface iron became detached, and stood open like a 
detached bark. A tough gray ligature with splintered surface 
connected the two ends, and a finger could be thrust under the 
skin on either side. 

Several photographs were made of instances of this action ; it 
being deemed peculiar to most excellent iron, occurring only 
with A, C, F, Fx, and O. 

Crystallization. 

The question as to whether crystallization can be produced in 
iron by stress, or by repetition of stress with alternations of 
rest, or by vibration, has been much discussed, and very oppo- 
site views are entertained by experts. 

We have met but with one unmistakable instance of crystal- 
lization which was probably produced by alternations of severe 
stress, sudden strains, recoils, and rest. 

The connecting-rod of the chain-prover was five inches in 
diameter, and had been in use for forty years, and had, during 
this period, been frequently subjected to stress up to 250,000 
pounds, with recoils produced by rupture of test pieces. 

It was carefully made in the anchor-shop, being hammered 
from the best quality of wrought-iron scrap. It is not probable 
than any section of it, if broken when first made, would have 
displayed crystalline structure ; but, while we were testing, it 
parted one day at less than 200,000 pounds stress, and the 



TESTS OF BAES BY IMPACT. 37 

surface of the fractured ends showed well-defined crystalliza- 
tion, the facets being large and bright as mica. The ends hav- 
ing become injured by rust, the bar was again broken by impact 
at a point distant over a foot from the first fracture, and the 
same appearance was found. The original of this fracture is 
now in the cabinet of Stevens Institute of Technology. 

Impact Tests. 

The records of tests by impact begin with the history of an 
examination made upon the contract chain-iron in store, made 
by the chairman of these committees, acting under the instruc- 
tions of the Navy Department, with the object of ascertaining 
the character of the iron on hand, and the effect of thorough 
re-working upon such as was found unsuitable for cables. 

This iron was stowed in piles classified by diameters. Most 
of it had been received during the war from such contractors 
as had bid lowest, and its origin beyond this point was unknown : 
its general character, as found by this examination, was worth- 
less in its present state. The results of the experiments in 
re-working, and in combining it with scrap-iron of a superior 
quality, were such that the iron produced was pronounced by 
the Chief of the Bureau of Steam Engineering as "at least 
equal, if not superior, to the best commercial iron, at less cost." 

[The original report contains the records of about a thousand 
impact tests. From these the abridger has selected the records 
of irons F and M, as showing the variation of resistance to 
impact between a soft, ductile iron, and a hard, brittle iron.] 



88 



WEOUGHT-moX AND CHAIX-CABLES. 



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TESTS. OF BAES BY IMPACT. 



39 



IRON M. — UNSCORED. 





« 


Force and Effect oi 


Blow 


'S. 


X 


First. 


Second. 


Thiri 


). 


ir 

o 


OQ 


rS A 


m 


, • 






Remabes. 






o ^ 






5.1 


o 


1 I 




5_ 


< 

5 






^ o 
o 


II ' 




§ 1 




1 


2i" 


3,000 


D 










. All bright granulous. 


2,2i 


2,500 


D 


.... 








All bright granulous. 


3^ 


2 


2,500 


D 


.... 








All bright granulous. 


4 


2 


2,000 


C 


500 


D 






. All bright granulous. 


5 


1| 


2,000 


c 


1,000 


D 






. 90 per cent bright granulous. 


6 


1| 


2,200 


F 


.... 


. . 






. 90 per cent bright granulous. 


7 


1^ 

^5 


2,000 


D 


.... 


. . 






80 per cent bright; the rest dark and dull. 


8 


13 


1,500 


C 


500 


D 








9 


If 


1,500 


c 


300 


F 






80 per cent bright ; the rest dull, short fibre. 


10 


1* 


1,600 


D 


.... 


.. 








11 




1,700 


D 





•• 






About equally mixed, dark short fibre, and bright 
granulous. 


12 


1| 


1,000 


C 


1,000 


+ 


6( 


)0 


F 


13 




1,200 


D 


.... 


, . 


. 


. 


. All bright granulous ; very short. 


i4 


Ig 


1,000 


D 


.... 


• . . 


, , 


, 


. 90 per cent bright granulous ; very short. 


15 


If 


800 


D 


.... 


. . . 




. 


Bright granulous ; very short. 


16 




600 


F 


.... 


. . < 


, , 


, , 


. 


17 


l| 


500 


C 


300 


F . 




. , 


. 90 per cent bright ; the rest dull fibre on one side. 


18 H 


400 


c 


400 


+ 


4( 


)0 


F 90 per cent bright granulous. 


19 li 


600 


D 


• • • • 


. . < 


, , 


, , 


Mixed dull fibre and bright granulous. 


20 li 


500 


T 


• • • » 


• • • 


• 


• * 


. End just hanging on by small bit of fibre; the rest 
bright granulous. 



Explanation of Symbols used in the above Tables. 

The figures under " effect and deflection " are deflections in degrees, from horizontal. 

*' S.C," a slight crack in which a needle-point could be inserted, and 

" C," a crack wide and deep enough to insert the edge of a khife. 

'* +," an increase in the oi^ening, but not enough to term 

" B.C.," a bad crack. 

•• F.," a fracture in which the ends are torn apart, leaving long, jagged splinters. 

•• 5F.," an incomplete fracture of the same nature, the ends still remaining connected. 

" D," a short square break, with little or no deflection, the fractured surfaces showing smooth 
as if cut in two. 

*' Closed to hammer," the test-piece is bent to from 110° to 120°, and in contact with the face of 
the wedge of the hammer. 

" Closed down," the piece has been still further closed under the steam hammer, until the 
Bides are in contact the whole length. 



40 WKOUGHT-mON AND CHAIX-CABLES. 



SECTION lY. 

A Paper describing a Series of Experiments to determine Facts in regard to ike 
Operation of the Law called the Elevation of the Limit of Stress. 

The discovery that wrought-iron, after having been subject- 
ed to a steady stress up to the point of its ultimate strength, 
would, if then released from stress and permitted to rest, expe- 
rience an elevation in both its elastic and tensile limit, was made 
by Professor Eobert H. Thurston in November, 1873, and by 
the chairman of these committees a short time afterward, while 
carrying on an investigation by tension. Professor Thurston 
having made his discovery by torsion tests. The discoveries 
were entirely independent, neither experimenter having any 
knowledge of the other's work. 

As, at the beginning of the series of tests incorporated in this 
report, but little data had been obtained as to the operation of 
this new law, it was thought worth while, while making investi- 
gations in regard to chain-iron, to utilize at slight expense many 
of the test-pieces, in investigating its action. By bringing a 
test-piece to the tensile limit, all data as to its strength are 
obtained ; and by carrying the test to rupture, we gain simply 
the dimensions after rupture, and means to reduce the strength, 
&c., to those measurements. 

We therefore released a number of test-pieces from stress, 
when the tensile limit was reached, and, preserving them for 
various periods, eventually broke them, with results as given in 
the following paper ; — 



ELEVATION OF THE LBHT OF STEESS. 41 



Elevation of the Limit of the Stkess. 

Uxperiments JVbs. 1 to 10. 

Twelve test-pieces which had been strained to the point of 
"tensile limit" while testing irons C, D, and K, were permitted 
to rest free from strain for from twenty-four to thirty hours, 
then broken with results as follows : — 

No. 1. Iron C, 2''; strength second day over that at first test, 
3,357 pounds per square inch, or ^Jo per cent. 

No. 2. Iron C, IJ''; strength second day over that at first test, 
2,238 pounds per square inch, or 4.4 per cent. 

No. 3. Iron C, 1^^'; strength second day over that at first test, 
7,506 pounds per square inch, or 15.1 per cent. 

No. 4. Iron C, 1^ ; strength second day over that at first test, 
8,560 pounds per square inch, or 17 per cent. 

No. 5. Iron D, 2'' ; strength second day over that at first test, 
952 pounds per square inch, or 2 per cent. 

No. 6. Iron D, IJ''; strength second day over that at first test, 
7,354 pounds per square inch, or 15.7 per cent. 

No. 7. Iron D, 1|^'; strength second day over that at first test, 
7,773 pounds per square inch, or 16.1 per cent. 

No. 8. Iron D, 1|''; strength second day over that at first test, 
8,605 pounds per square inch, or 16.7 per cent. 

No. 9. Iron D, IJ''; strength second day over that at first test, 
6,904 pounds per square inch, or 14.1 per cent. 

No. 10. Iron D, 1^'^; strength second day over that at first 
test, 8,325 pounds per square inch, or 16.3 per cent. 

No. 11. Iron K, \^' \ strength second day over that at first 
test, 4,203 pounds per square inch, or 8.2 per cent. 

No. 12. Iron K, V \ strength second day over that at first 
test, 5,040 pounds per square inch, or 8.8 per cent. 

Nos. 11 and 12 were of a fine, strong iron, with considerable 
carbon, breaking with a steel-like fracture : the remainder were 
all from tough, fibrous iron. The indications were that the lat- 
ter type of iron gained the most by the rest. While testing 



42 TTROUGHT-mON AND CHAIN-CABLES. 

the foregoing pieces, tlie stress which produced the first per- 
ceptible elongation (about .002 of an inch) was observed; and 
on the first test this stress was from 61 to 70, averaging about 
65 per cent of the ultimate strength. Upon testing them the 
second time, the stress whioli produced first stretch was nearly 
identical with the ultimate strength. 

Second Experiment. — Forty-two test-pieces of iron F, which 
was of remarkably uniform structure, were, after having been 
strained to "tensile limit," allowed to rest for periods varying 
from one minute to six months^ when they were re-tested with 
results as per table. 

Elevation of the Limit of Stress. Iron F. Abstract from Detail of Tests. 

Average gain in less than one hour . 

Average gain in less than eight and over one hour, 3.8 

Average gain in three days .... 

Average gain in eight days .... 

Average gain in over eight and less than forty 
three days ....... 

Average gain in six months .... 

42 

The elongation was irregular ; that of those broken at first 
stress and of those after six months' rest coinciding at 29 per 
cent, while intermediates varied from 27.5 per cent to 30 per 
cent. 

Having failed to procure data as to the effect of rest after 
strain, for periods between eight hours and three days, it was 
resolved to fill the hiatus with a series made upon iron D, which 
resembled iron F, except in possessing somewhat greater te- 
nacity when tested as an entire bar. 

Seven test-pieces were brought to tensile limit upon one day, 
and broken after twenty-four hours of rest, with an average 
gain of 15.4 per cent. This is but slightly below that of the 
pieces of iron F rested three days (16.2 per cent) ; and we may 
consider that at the end of one day the result is, with very 
ductile irons, practically accomplished. 



'ER CENT. 


TESTS. 


1.1 


5 


, 3.8 


8 


1G.2 


10 


17.8 


2 


15.3 


5 


17.9 


12 



ELEVATION OF THE LIMIT OF STRESS. 



43 



Reduction of Strength between the Ultimate reached^ and 

Bredking-jyoint. 

Six of the forty-two pieces were, after reacliing the tensile 
limit, on the second test, still further tested thus : The lever 
having fallen, weights were removed until a balance took place, 
which balance Avas maintained by removal of weights w^hile the 
crank was turned without cessation, but slowly ; and the speci- 
mens finally ruptured at strains considerably less than the 
original strength, thus : — 



Interval between First 


Original 

Strength. 


Strength at 
Rupture. 


Loss. 


AND Second Tests. 


Pounds. 


Per Cent. 


1 hour 

2 hours 

3 " 

4 " 

5 " 

6 " 


Pounds. 

49,345 
49,358 
49,401 
49,206 
50,257 
50,313 


Pounds. 
42.952 
43,049 
42,271 
42,364 
42,914 
43,121 


6,393 
6,309 
7,130 
6,842 
7,343 
7,192 


12.9 
12.9 
14.4 
13.9 
14.5 
14.2 


Average .... 






6,868 


13.8 



Percentage of Change of Form at Tensile Limit to that at 

Fracture. 

At tensile limit the average reduction of area which had 
taken place was equal to 53 per cent of that at rupture, and the 
average percentage of elongation was 80 per cent. 

The average of the same percentages upon the twenty-three 
pieces broken by single continued strain was, of reduction of 
area, 49 per cent ; of elongation, 78 per cent : from which aver- 
ages we deduce, that, at the instant of ceasing to resist an in- 
crease of stress, the reduction of area wdiich has taken place 
is about one-half, and of elongation a little over three-quarters, 
of that which will have occurred if the metal be further 



44 WKOUGHT-IRON AND CHAIN-CABLES. 

strained to rupture. This, we believe, will not prove true if the 
metal is ruptured by a sudden strain, by the action of which 
the fractured dimensions will nearly coincide with those whicli 
would have existed at tensile limit had the piece been broken 
by steady strains. This was indicated by the results of an ex- 
periment with an apparatus which we devised, by which we were 
enabled to apply sudden strains to the specimen. 

By means of a pair of spring clamps, a holder was attached 
to the upper and lower clamps of the dynamometer; and the 
stress produced by turning the crank, or some indefinite por- 
tion of it, was accumulated in the legs of this holder, and at 
will transferred suddenly to the specimen. The machine was 
imperfect, its use involved risk of injury to the dynamometer, 
and we made but one test with it, which was as follows : — 

Comparison of Effect of Steady and Sudden Strains upon Change 

of Form, 

Two specimens of nearly the same dimensions were turned 
from iron E. 

No. 1, having diameter .h^b" , length 2.27''. 

No. 2, having diameter .565'', length 2.25". 

Xo. 1 was broken by steady tension, and at tensile limit its 
diameter was .498", length 2.80". No. 2 was broken by a series 
of jerks, and its ruptured dimensions were, diameter .496", 
length 2.87"; the ruptured dimensions of No. 1 being, diameter 
.407", length 3.00". 

Comparison of Elevation of Limit of Stress, upon Irons of differ- 
ing Characteristics, 
The first series of experiments (Nos. 1 to 12) gave indica- 
tions that the operation of the law was less felt by coarse and 
brittle irons, and by those of a steely structure, than by those 
of a more fibrous ductile texture. Tliis was considered to be 
a point Avorthy of careful examination, and a series of com- 
parative experiments Avas made upon test-pieces composed of 
the three varieties of iron. Thirteen pieces were prepared, 



ELEYATIOX OF THE LIMIT OF STEESS. 



45 



five of wliicli were of soft charcoal bloom boiler-iron, five of 
coarse contract chain-iron, and three of a fine-grained bar of 
iron K, a very pure iron with high tenacity. These pieces 
were all made of uniform proportions, and were tested to ten- 
sile limit upon the same day. They were then allowed to rest 
eighteen hours, and again tested. Some were broken at this 
second test ; others released from stress at tensile limit, and fur- 
ther tested after varying periods of rest, as per following table, 
in which Nos. 62 to 66 were of the boiler-iron, 67 to 71 of the 
contract chain, and 72 to 74 of iron K. 



Effect of Uniform Rest upon Irons of widely different Character. 

TEST-PIECES RESTED EIOHTEEN HOURS. 



Number and 


Marks 




Ultimate Strength 
PER Square Inch. 


Gain in Strength 
PER Square Inch. 


Remarks. 




First 
Strain. 


Second 
Strain. 


Pounds. 


Per Cent. 




62, Boiler iron 
63, 

64, " 

65, •• 
66, 

67, Contract ch£ 

68, 

69, 

70, 

71, «' 

72, Iron K . 

73, " 


lin iron 

<( 

(< 

<( 




Pounds. 

48,600 
49,800 
49,800 
48,100 
48,150 
50,200 
50,250 
50,700 
49,600 
51,200 
58,800 
59,000 
56,400 


Pounds. 

56,500 
57,000 
58,000 
54,400 
55,550 
54,000 
53,200 
55.300 
52,900 
52,800 
64,500 
65,800 
60,600 


7,900 
7,200 
9,200 
6,300 
7,400 
3,800 
2,950 
4,600 
3,.3O0 
1,600 
5,700 
6,800 
4,200 


16.0 

16.4 

18.4 

13.1 

15.0 

7.5 

5.8 

9.0 

6.6 

3.2 

9.6 

11.5 

7.3 


Not broken. 

Broken."] 

Broken. 1 Average 

Broken. [ 15.8 per cent. 

Broken. J 

Broken. 

Not broken. Avprqsrp 

^ot broken. '^ 
Not broken. 

H"t!!;\ Average 


74. •' .... 









These experiments confirmed the opinion already formed, 
and indicate that a bridge, cable, or other structure composed 
of iron of either of the latter two varieties, will receive com- 
paratively slight benefit from the operation of this laAv; while 
ductile, fibrous metal, Avhicli possesses greater inherent power 
to resist sudden strains than does the iron of a coarser nature, 
although the latter may be better able to resist steady stress, 
gains in tins latter power to a greater extent by the effect of 
strains already withstood. 



46 WROUGHT-IRON AND CHAIN-CABLES. 

Supplemental Tests of JVos. 62, 68, 69, 70, and 71, of foregoing 

Test-Pieces. 

No. 62, after having been strained to the tensile limit the 
second time, was released from stress, and re-tested after one 
year 8 rest, when its ultimate strength was found to be 59,500 
pounds, a total gain of 22 per' cent upon the original strength. 

No. 68 was rested for 7 hours, 41 hours, and 24 hours, 
and after each rest repulled to the tensile limit, with results as 
follows (the first two tests being included for ready compar- 
ison) : Strength, first strain, 50,250 pounds ; rested 18 hours, 
strength 53,200 pounds ; rested 7 hours, strength 54,700 pounds ; 
rested 41 hours, strength 54,500 pounds; rested 24 hours, 
strength 54,000 pounds. 

No. 69. First strain, strength 50,700 pounds ; rested 18 hours, 
strength 55,300 pounds; rested 7 hours, strength 53,150 
pounds; rested 41 hours, strength 56,600 pounds; rested 24 
hours, strength 54,000 pounds. 

No. 70. First strain, strength 49,600 pounds ; rested 18 
hours, strength 52,900 pounds; rested 8 hours, strength 51,000 
pounds; rested 16 hours, strength 54,800 pounds; rested 24 
hours, strength 53,000 pounds. 

No. 71. First strain, strength 51,200 pounds ; rested 18 hours, 
strength 52,800 pounds ; rested 8 hours, strength 54,900 pounds ; 
rested 16 hours, strength 52,750 pounds; rested 24 hours, 
strength 51,750 pounds. 

The four pieces were broken at the strains last given. 

Experiments with Two Sets of Test-Pieces : One Set cut from 

Bars in their Normal Condition, the other from the same Bars 

after the Latter had been p)ulled asunder by Tension. 

Nineteen bars of various irons were selected, and from each 

a cylindrical test-piece was prepared : the bars were then fitted 

with heads, and pulled asunder by tension. Another set of 

cylinders was prepared by cutting the necessary length from 

one of the broken ends, about six inches from the point of rup- 



ELEVATION OF THE LIMIT OF STRESS. 



47 



ture. Both sets of cylinders were tested, with results as per 
following table, showing a great gain in strength in all cases 
when the material could be classed as wrought-iron, but none 
when it was steel. Hence we infer that excess of carbon de- 
prives iron of the power to gain strength through the action of 
this law. 

Experiments Nos. 75 to 96. — Comparison of Strength of Two Sets of Test- 
Pieces, the first of which icas cut from Bars in their Normal Condition, and 
the second from the same Bars after the latter had been pulled in Two. 









Stress required to Break 


Strength of 


Second Set 








THE Test - Pieces per 


OVER First. 


XO. OF 


Size of 
Bar. 


XA5IE OF 

Ikon. 


Square Inch. 






Test. 
















First Set. 


Second Set. 


Pounds. 


Per Cent. 




Inch. 




Pounds. 


Pounds. 


Per Sq. Inch. 




75 


If 


K 


53,520 


72,700 


19,180 


35.8 


76 


iH 


K 


53,920 


71,800 


17,880 


33.1 


77 


i4 


C 


47,875 


63,560 


15,685 


32.7 


78 


^16 

If 


C 


48,600 


65,000 


16,400 


33.7 


79 


4 
1| 


C 


56,000 


73,000 


17,000 


30.3 


80 


l| 


C 


52,000 


67,900 


15,900 


30.6 


81 


A 


C 


45,800 


63,300 


17,500 


36 


82 


1 1 


B 


51,900 


72,000 


20,100 


38.7 


83 


16 
l^i 


B 


53,000 


68,700 


15,100 


28.1 


84 


If 


J 


50,350 


68,400 


18,050 


35.8 


85 


l| 


J 


50,400 


67,700 


17,300 


34.3 


80 


14 


F 


50,180 


66,400 


16,220 


32.3 


87 


li 


F 


50,400 


67,200 


16,800 


33 3 


88 


li 


E 


50,080 


68,000 


17,920 


35.7 


89 


li 


E 


50,100 


70,100 


20,000 


39.9 


90 


1?3 


L 


58,390 


69,200 


10,810 


18.5 


91 


if 


L 


59,290 


67,160 


7,870 


13.2 


92 


4 


L 


75,233 


76,600 




.... 


93 


1? 


L 


84,800 






.... 


94 


i| 


L 


74,600 


72,600 


Decrease. 





95 


i5_ 


L 


66,500 






.... 


90 


ill 

16 


L 


66,800 


73,900 


5,250 


7.9 



The test-pieces from Nos. 75 to 89 inclusive were made from 
ordinary commercial bar-iron of various degrees of ductility. 
All show a remarkably great strength, caused by tension upon 
the entire bars. 



48 



WROUGHT-IROX AND CHAIN-CABLES. 



The interval of time between the two sets of tests was not 
noted, but it was several days. 

There is no marked difference in the amount of elevation, 
except upon the test-pieces made from L, which was a weld- 
steel, although sent to us as chain-iron. With this metal the 
results were exceedingly irregular, and it was thought advisable 
to make a few careful tests upon it. Four pieces were there- 
fore prepared from a bar of |'' diameter, which were tested to 
the tensile limit, and then rested for one hour, one day, one 
week, and one month, respectively, when they were re-tested 
with results as follows : — 

Experiments Nos. 97 to 100. Material ^^ Iron'' L (Weld Steel). 





Original 
Dimensions. 


Strength per 
Square Inch. 


Period of Rest. 


Gain in 
Strength. 




Diameter. 


Length. 


At first 
Test. 


At second 
Test. 


Pounds. 


Per Cent. 


97 

98 

99 

100 


Inches. 

.500 
.500 
.496 
.501 


2.25 
2.25 
2.25 
2^25 


Pounds. 

59,078 
58.569 
59,000 
59,859 


Pounds. 

58.619 
57,805 
59,653 
61,694 


1 hour .... 
1 day . .^ . . 
1 w eek .... 
1 month . . . 


-459 

-764 

+ 653 

+ 1,834 


'i! 

3. 



The entire series of tests by tension upon this metal indicates 
such irregularity in its strength that the foregoing tests do not 
possess a positive value ; but they indicate that there is a great 
cliiference between the action of weld-steel and even steely 
irons, and still greater between it and fibrous iron when ex- 
amined in reference tc the action of this law. We obtain no 
positive evidence that any increase of strength is caused in 
steel, by rest after strain. 



THE CABLE. 49 



SECTION Y. 

THE CABLE. 

The information which we have gained by the results of our 
tests of round bars has its value in determining the char- 
acteristics of a suitable cable-iron, but it does not supply us 
with all that we need. 

The cable-link consists of a round bolt, twelve diameters in 
length, which has been bent into an oval form, and the ends 
welded together. A stud or stay is introduced between the 
sides, to prevent closure under stress, and kinking, while the 
cable is being handled or used. 

The tension tests upon the bars show us wdiat strength 
should exist in each of the sides of the link ; and the impact 
tests give us an idea as to the power of the transverse sections 
of the ends to resist stress suddenly applied, if^ the process by 
which the bar is transformed to a link has no jDower to change 
the qualities as found in the bars. 

This process involves twice reheating and hammering the 
ends of the bolts, — once to make the scarfs, and once to make 
the welds, while the butt end of the link has at the same time 
with the ends been heated once for bending. This forging and 
re-heating has a tendency to lower the elastic limit and strength 
of the two ends of the bolt upon which the weld is made ; the 
process of bending affects some irons injuriously; and the com- 
paratively incompressible stud, which prevents closure, alters 
the nature of the strains. 

If none of these causes reduced the strength of a link, and 



50 



WROUGHT-IPvON AND CHAIN-CABLES. 



the single area of each end should be so strengthened by its 
arched form that it would be equal to the two sides combined, 
the strength would be just twice that of the bar from which it 
was made. 

A suitable chain-iron is one which will develop in the link 
form the greatest and most uniform proportion of this two 
hundred per cent. And the development of a low or irregular 
proportion indicates that the iron is not suitable. The diver- 
gence from the two hundred per cent marks the extent to 
which an iron can be called suitable. 

The causes which operate upon all irons to reduce their per- 
centage are, first, the weld ; second, the stud. We have tested 
a large number of chain-links to destruction, and their action 
under the strain of tension has been carefully noted. We find 
that the lowest percentages of the bar's strength are developed 
by those irons which do not permit strong and thorough weld- 
ing by ordinary processes ; and that, in breaking links of all 
variety of irons, the weld end is generally the weak part of the 
link ; and that with certain types of iron this weakness is so 
great and of so frequent occurrence that cables made from such 
iron are very unreliable. 

In the rupture of 435 links, 333 of 
them broke at the weld end, 86 at the 
butt end, and 16 on the side. 

The most ordinary location of the 
rupture, if we except irons Fx, F, L, 
M, and Px, was at the quarter of the 
weld ; which rupture is produced by a 
resolution of the force of direct ten- 
sion and the resistance opposed by the 
stud. 

The sketch will show the parts of the 
links designated as quarter weld, &c. 
An examination of the records of 
the strength of links, and of the percentage of the bar's 
strength developed by the links, will show that all of those 




THE CABLE. 51 

links which broke " through the weld " were very weak and 
irregular in both factors. Hence an iron whose weld is 
through any cause unreliable is not suitable for cable. 

Experiments indicate that we cannot strengthen the link by 
changing the location of the weld, and our only resource is to 
select such iron as is least injured by the process of welding. 

Among the causes which produce deficiency in welding 
properties, there are two which produce great tenacity in the 
bar, viz., chemical peculiarities and excessive work : therefore, 
when excessive tensile strength is found to exist in a bar as 
tested by tension, it should be regarded as a probable indication 
of deficient welding properties. As may be seen by the records 
of tension and impact compared, high tenacity in the bar fre- 
quently indicates a lack of power to resist sudden strains. 
Therefore, in judging iron by tensile strength alone, it should 
be considered as more than probable that the strongest bars loill 
produce the iveahest cables, although there will undoubtedly be 
in each of such a few links with greater strength than can be 
developed by irons of less tenacity. 

The second cause which tends to prevent the link from 
developing twice the strength of the bar is the stud. 

Our experiments lead us to consider that the opinion Avhich 
is generally entertained, and which is backed by the most emi- 
nent authorities, that the studded link is stronger than the 
unstudded one made from the same iron, is erroneous, both in 
principle and in fact. 

Rankine, in his "Manual of Machinery" says, "An unstud- 
ded chain has about two-thirds of the strength of a studded 
chain of the same diameter of wire." John Anderson, LL.D., 
superintendent of machinery to the War Department, Wool- 
wich, in a work published in 1872, says, ''It is to be noted, 
whatever the explanation may be, that the stayed-link chain, 
when made of the same diameter of iron as the open-link, is 
stronger than the other in the proportion of 9 to 6. The oftice 
of the stud is to prevent the collapse of the link, and thereby 
intercept the shearing action due to the wedge action of one 
link within the other." 



52 WROUGHT-IFtOX AND CHAIN-CABLES. 

American authorities coincide with the above opinions, with 
which, however, we entirely differ. Theoretically it should not 
be stronger, actually it is weaker, than the open-link. 

Theory indicates that when "the links are without studs they 
might stretch until they nipped each other, and then be in the 
best possible position to resist stress ; the sides being parallel and 
separated but by their own diameter, the ends so closed together 
that the stress is received and transmitted through bearing sur- 
faces much greater than before the parts had yielded to stress. 

Our experience in testing cable links showed us that with all 
classes of iron this tendency to assume the strongest possible 
form existed, but in very different degrees ; and in this differ- 
ence we find a possible reason for the different conclusions that 
have been arrived at by the English experimenters and by our- 
selves. The English use for chain-cables iron of great tenacity, 
and the studs to their links are made of malleable iron. 

Qur experiments have been made both with links of iron of 
similar character, and with others made from iron with medium 
and low tenacity, but with great ductilit}^ and power of flexure. 
In all cases we have, however, used the ordinary cast-iron stud. 

Experiments made upon iron of a soft ductile type showed 
that the excess of the strength of the unstudded link over that 
of the studded ranged from twelve to seventeen per cent, 
averaging about fifteen per cent, of the strength of the studded 
links ; while with links made of iron of a coarse, hard type the 
excess of strength was about five per cent, as shown by the 
following tests. 

Experiments upon Comparative Strength of studded 

AND unstudded LiNKS MADE FROM SOFT DUCTILE IrONS 

(C AND F) ; Diameter of Iron, IJ''. 

The links were arranged in seven sections, of three links 
each ; of which the centre link was in each case an open one, 
and the two end links (E L) were connected to the proving-bar 
by means of links of considerably greater diameter (1^'g''). 

After pulling each section until one of the links broke, the 



THE CABLE. 



53 



pair remaining was again pulled till one broke, and finally the 
unbroken remaining link was broken. 

The results of the tests were as follows : — 



Test 
No. 




Number 


Link 


Stress ' 


Test 
No. 




Number 


Link 


Stress 


and Arrangement of 


wliicti 


at 


and Arrangement of 


which 


at 




Links. 


Broke. 


Rupture. 




Links. 


Broke. 


Rupture. 










Pounds. 








Pounds. 


1 


3 


Stud, Open, Stud, 


S. 


87,360 


4 


1 


O. 


E. L. 


96,000 


1 


2 


o. S. 


S. 


89,088 


4 


1 


O. 


O. 


104,000 


1 


1 


O. 


E. L. 


86,400 


5 


3 


S. 0. s. 


S. 


90,624 


1 


1 


0. 


E. L. 


74,880 


5 


1 


o. 


o. 


105,576 


2 


3 


S. 0. s. 


S. 


91,584 


6 


3 


S. 0. s. 


s. 


82,176 


2 


2 


O. 0. 


o. 


99,844 


6 


2 


0. s. 


s. 


91.776 


2 


1 


o. 


E. L. 


77,280 


6 


1 


0. 


o. 


100,128 


2 


1 


o. 


O. 


82,170 


7 


3 


S. 0. s. 


s. 


79,488 


3 


3 


S. 0. S. 


8. 


96,960 


7 


2 


0.0. 


o. 


105,600 


3 


2 


o. o. 


E. L. 


92,544 


7 


1 


o. 


E. L. 


67,200 


3 


2 


O. 0. 


O. 


104,064 


7 


1 


o. 


E. L. 


89,280 


4 


3 


S. 0. s. 


Pin 


85,632 


7 


1 


o. 


Pin 


82,176 


4 


3 


S. 0. S. 


S. 


98,688 


7 


1 


0. 


O. 


109,632 



The bar from which sections Nos. 1 and 2 were made had a 
tensile strength of 59,000 pounds ; Nos. 3 and 4 were from bars 
with 57,000 pounds ; Nos. 5 and 6 from bars with 54,000 pounds ; 
and No. 7 from a bar with 57,700 pounds tensile strength. 

In every ease in which there were both open and studded 
links connected, the studded link first broke. In six tests, the 
open link of IJ^' diameter, of good iron, broke the l^^g'' link of 
inferior iron, and twice the shackle-pin of steel. 

The maximum strength of the studded links on the first pull 
was 96,960 pounds; the minimum, 79,488 pounds; the average 
of six, 88,030 pounds. 

In three cases where a studded link was pulled the second 
time, the maximum strength was 98,688 pounds ; the minimum, 
89,088 pounds ; and the average, 93,188 pounds. 

The maximum strength found in an open link was 109,632 
pounds, on a sixth pull ; the next was 105,576 pounds on a 
second pull; and the minimum, upon any pull, was 82,170 
pounds — the average strength of eight being 101,327 pounds; 
the inferior iron (contract chain-iron), of which the end links 
were made, breaking upon second and third pulls, at from 
67,200 pounds to 96,000 pounds, averaging 82,383 pounds. 



54 WROUGHT-IRON AND CHAIN-CABLES. 

From which we deduce, that, of the same iron, an unstudded 
cable would have exceeded in strength the studded one, in 
actual strength, over 13,000 pounds, or 15 per cent ; and that 
after having been subjected to stress sufficient to break the 
studded links, the unstudded cable would have still proved 
reliable ; and, further, that a vessel provided with a studded 
cable made of this good chain-iron of IJ'' diameter, of which 
150 fathoms would weigh five tons, would have possessed more 
reliable ground-tackle than if the cable had been of the lyV' 
contract-iron, weighing eight tons. 

During the experiment recorded, several times it happened, 
that, either through the stress or the recoil, one of the studded 
links became an open one, by the stud splitting and flying out. 

In addition to the evidence given, abstracts from our tests 
show that in breaking thirty-three sections of links of iron 
Fx, D, O, and N, which Avere composed of both studded and 
unstudded links, in twenty-nine cases the link which broke was 
a studded one. 

From the facts recorded, we feel that we are justified in 
saying, that beyond doubt, wdien made of American bar-iron, 
with cast-iron studs, the studded link is inferior to the un- 
studded one in strength. 

Therefore we place the stud as next to the weld among the 
elements which tend to prevent the individual links from de- 
veloping the utmost possible strength. 

Description of Method of Testing Cables. 

Our records embrace the results of strength, &e., obtained 
by the rupture of 229 sections of cables, of various diameters 
and lengths, made from eighteen different irons. 

These are given in the tabulated record of breaking strains, 
arranged in the order of the relative strength. 

The history of the test, as cable, of one of the irons (Fx), is 
given in detail below. 

The links were generally arranged as shown in the cuts ; the 
end links, Nos. 1 and 5, and centre link, No. 3, being unstud- 



THE CABLE. 



55 



ded, the others studded. The end links were, in some cases, 
of greater diameter than the links to be tested, in which case 
they were not recorded in the number of links in section. 




After we had decided upon the superior strength of the 
unstuclded link, our test-sections were prepared with end links 
of the same size and iron as the other links, but without studs. 

The shackle-pins were oval, and made to correspond with the 
diameter of the links. 



Test as Cable of Iron Ex. Linls arrariged as per Sketch. Elongalion re- 
corded ichen .03" icas observed on No. 2 Link. 



o 

P5 . 


o 




Elongatiox or 


li. 


si 

o 




Elongation of Un- 
broken Links. 


E- O 

H £3 


!N 


eo 


rj! 


<N 


CO 


•4 


< 


^ 


-5 


1 


o 


O 


1 
H 

CO 


C 2 


k1 


o 


i 


6 


n 




Pounds. 


n 


i> 


II 


Pounds. 






II 


II 


„ 


1 


3 


34,800 


.03 


.11 i .03 


70,300 


4 


Q. W. 


.50 


.62 


. . 


H 


3 


44,400 


.03 


.10 


.03 


81,400 


2 


T. W. 


, , 


.70 


.72 


H 


3 


61,100 


.03 


.14 


.05 


111,000 


2 


Q.B. 


, , 


1.00 


.70 


^ 


3 


78,000 


.05 


.24 


.03 1 124,000 


3 


W. 


1.45 




.75 


H 


3 


80,000 


03 


.28 


.04 1 153,000 


2 


Q.W 


, , 


1.15 


1.00 


1* 


3 


98,000 


.03 


.28 


.06 168,000 


2 


Q. W 


, . 


1.85 


1.25 


If 


3 


100,000 


.03 


.26 


.04 


185,000 


2 


Q. W. 


, , 


1.20 


1.40 


4 


3 


110,000 


.03 


.22 


.03 


205.600 


3 


T. W. 


1.60 


, , 


1.30 


o" 


3 


117,200 


.03 


.19 


.04 


240,000* 




• • 


1.50 


1.70 


1.60 



These tests indicate, that with ordinary chain-iron, although 
the first stretch of the open link is produced by a much lower 
stress than that which the studded one withstands, yet, upon 

* Not broken. 

Five ruptures occurred on link No. 2, one on No. 4 studded, and two on open links, in one 
of which the weld drew. The elongation produced upon the open links by the stress which 
broke the studded ones was not sufficient to greatly impair their usefulness: the 1", with 
original inner diameter of 1.55", being reduced to 1.40"; the I5", original inner diameter 2.8", 
after stress, 2.50"; and the others in proportion, there being sufficient room for the links to 
traverse freely. 



56 



WROUGHT-IROX AND CHAIN-CABLES. 



the strain becoming more severe, the disproportion in its effects 
becomes less, and that frequently the open link is still service- 
able after the studded link has broken. 

The following abstract shows the extreme variation that ^ve 
have found in the strength of cable of the same size, made from 
several irons. We gather from it that a variation of from 
five to seventeen per cent may be expected in the strength of 
ordinar}* cables ; and that, if proper care is not exercised in 
selecting the material, the average variation may rise from 
twelve to twenty-five per cent of the strength of the 

strongest. 

Variation in Strength of Cables. 



i « 


a) 

c c 

1—1 t- 


Strength 


OF Cable. 


Variation in 
Strength. 




Variatiox in 
Strength byiinclud- 

ING OMITTED LiNKS. 


Size of Ca 


eg 

c2 a 

a a 

1^ 










< M 






i 

1 




3B 

1— ( 




3 





/' 




Pounds. 


Pounds. 












1 


6 


79,200 


67,600 


11.600 


14. 


P. 


18.800 


23.7 


H 


7 


89,280 


80.900 


8,380 


9.4 


P. 


13.200 


14.7 


4 


7 


122.100 


101,700 


20,400 


16.6 


K. M. 0. 


31,100 


25 


l>c 


1 


115.000 


109.000 


6,000 


5 


M. 


40.000 


34.7 


If 


9 


137,200 


125.000 


12,200 


8 


M. Fx. 


42,200 


30.7 


Wc 


2 


155,040 


139,400 


15,640 


10 


. 


, , 


, . 


H 


9 


173,000 


147,000 


26.000 


15 


M. K. P. 


38,400 


22.2 


1^ 


12 


199,000 


168,000 


31.000 


15.5 


M. 


74,000 


37 


iH 


2 


2U,160 


194,880 


19,280 


9 


, . 


. 


, 


^ 


8 


231,300 


191,000 


40,300 


17 


Fx. 


45,800 


19.7 


11 


2 


231.940 


204,400 


27,540 


12 


^ , 


. , 


, . 


17 


6 


252,960 


215.000 


37,960 


11 


Fx. 


47,360 


18.6 


2^ 


8 


283,200 


240,000 


43,200 


15 


• 


• 


• • 


Aver 


age 




• • 


• 


12.1 


• • 


• 


25.1 



The excessive variation in case of the If is due to the fact 
that a portion of a lot of excellent chain-iron, C, was composed 
of very inferior material, which was very irregular in strength ; 
the strongest link in the lot breaking at 231,300 pounds, and 
five out of eleven sections breaking at less than 200,000 pounds ; 
the minimum being that in the table, 191,000 pounds. 



THE CABLE. 



57 



No system of tests made upon cable-bolts alone would liave 
detected with certainty this inferior iron. Had the iron been 
furnished in thirty-feet bars, each bar would have produced 
sixteen bolts, with a remainder of twenty-four inches for test 
purposes, the test of which would have given valuable evidence 
of the character of the sixteen links. 

Weight of Chain-Cables. 

The chain-cables manufactured by the ordinary systems are 
very heavy ; and we are led by the results of our investigation 
to believe that their weight can be reduced advantageously, 
and as great, if not greater, safety be secured. 

The weight and dimensions of various portions of cables of 
different sizes, and of full cables, of the length ordinarily used, 
are given in the following table : — 



Nwiiber and Weujlit of Links in 150 FatJioms of Cahle. 





Number of 

Links in 150 

Fatuoms. 


o . 


Finished Links. 


'^ Z J 

^ z < 


Total Weight of 
150 Fathoms Cable. 


Oj 


Length. Vidth. 


Weight. 


Studded 
Link. 


Open Link. 


if 

if 
if 

19_ 

16 

ir 

113 
1' 

if 

2JL 


2,925 
2,775 
2,700 
2,550 
2.450 
2.325 
2,250 
2,100 
2,025 
1,950 
1,875 
1,800 
1.725 
1.650 
1,650 
1.575 
1,500 
1,500 
1.425 
1,350 


Pounds. 

.25 

.25 

.44 

.44 

.50 

.50 

.62 

.62 

.75 

.75 

1.06 

1.06 

1.25 

1.25 

1.50 

1.50 

2.09 

2.09 

2.25 

2.25 


5U" 

610 
■;i6 

7-5- 

Q 1 -^ 

loii 

11-s- 


Q 9 " 

In 
r 

4 2_ 

4 ' 

4" 

4il 

"l6 
614 
"l6 

* 16 

7t'6 

710 

' 16 
712 

* 16 


Pounds. 

2.90 

3.43 

4.22 

4.89 

5.68 

6.50 

7.52 

8.50 

9.70 

10.87 

12.45 

13.81 

15.47 

17.05 

19.00 

20.80 

23 32 

25.38 

27.72 

30.04 


191 

18^ 

18" 

17 

16 

151 

lo 

14 

IP 
1? 
11* 

11 
101 
10 
10 

I' 


Pounds. 

8.665 
9,701 
11,650 
12.726 
14.236 
15,442 
17,326 
18,256 
20,143 
21,697 
2.3.996 
25.510 
27.480 
28.933 
32.334 
33.744 
36,125 
39.215 
40.811 
41,864 


Pounds, 

7.934 
9,008 
10.462 
11,604 
13.020 
14.279 
15,931 
16,954 
18.624 
20,234 
22.008 
23.602 
25,330 
26.870 
29.859 
31.382 
32.990 
36.080 
37,605 
38,827 



58 aykought-irox and chain-cables. 

Methods by ^vhich the Weight of Cables can be se- 
duced IN A GREATER RaTIO THAN THE STRENGTH. 

Two methods of reducing the weight of chain-cables, without 
impairing their strength, present themselves as results of our 
experiments ; the first founded upon our investigation of the 
action of the rolls and our impact tests combined, and the 
second upon comparative experiments of the strength of studded 
and open links. 

I. We have found, that, when made from the same material, 
the large bars possess less strength, in proportion to their areas, 
than the small ones, as opposed to steady strain, and generally 
much less absolute power to resist sudden strains. 

The strength per square inch of a l§''-bar being 54,000 
pounds, that of the ^' would be 50,000 pounds, and the entire 
strength of the \%'\ 112,000 pounds; which is 71 per cent of 
that of the 2'', viz., 157,000 pounds. 

If the two bars, 2^' and \%'\ were equally valuable in every 
respect for cable, and both in link form developed the same 
percentage of the bar's strength, say ^1 63 per cent, the strength 
of the li" cable would be 182,600 pounds, which is 71 per cent 
of that of the 2'', viz., 256,000 pounds; while its weight, 23,996 
pounds, would be but 66.4 per cent of that of the 2^', viz., 
36,125 pounds. 

If it be considered that the loss in actual power to resist 
steady tension is not counterbalanced by the gain in reduced 
weight, the comparative powers to resist sudden strains should 
be considered. It is more than probable that the greater work 
given to the \%" will have so increased its ductility that its 
power to resist sudden strains will prove greater than that of 
the 2'' cable. 

These views are borne out by many of our experiments, from 
which we will select the bars of iron N for comparison. This 
iron was sent to us by a prominent manufacturer, in answer to 
an order for "samples of best cable-iron." 

The 2''-bar had tenacity 51,748 pounds, and, when broken by 



THE CABLE. 59 

tension, had a very slight reduction of area and elongation : 
broken by impact, it proved very brittle, and, while in no ways 
nicked or injured, would break like a pipe-stem by moderate 
blows. 

Tested as cable, the links developed but 141 per cent of the 
bar's strength ; viz., 232,000 pounds. 

The If'^-bar, with tenacity 56,344 pounds, when tested by 
tension, reduced in area to 60 per cent of the original, and 
elongated 23 per cent. 

Tested by impact, it proved fairly tough, deflecting to over 
60° before breaking, and, when circled with a score, resisted to 
a greater extent than did the 2'' in its normal condition. 

Tested as cable, the links developed 164 per cent of the bar's 
strength, breaking at 195,500 pounds, or at 84 per cent of the 
strength of the 2''. 

In this case, there can be no doubt but that the smaller and 
lighter cable would have proved the most reliable. 

Irregularity in strength is a great fault in cable-iron : this is 
more apt to occur in large than in small bars ; one reason for 
which is, that irregularity in heating the piles produces irregu- 
larity in strength, and to this the large bars are more greatly 
exposed than the small ones. The pile and resultant bar of 2'' 
weighs four or five hundred pounds, and, while passing through 
the roll, is, of course, much more difficult to handle than a 
lighter pile or bar; there are greater liabilities of "buckling" 
and " bending;" and, while the workmen are mauling the bar to 
straighten it, tlie next bar to be rolled is being delayed in the 
furnace, and the effects of variation in the heat are not pro- 
vided against by regulating the latter. It seems but natural, 
that, if the pile for a small bar is heated enough for rolling 
in one hour, portions of the large pile are, in the same time, 
equally ready, and that by longer delay in the furnace they 
become overheated. 

The effect of overheating is to lower both the elastic limit 
and the strength. 

Irregularity in the workmanship by which the links are 



60 WROUGHT-IEON AXD CHAIN-CAELES. 

manufactured produces irregular strength in the cable. To 
this the larger bars are exposed to a greater extent than the 
smaller ones : the lueld is less apt to be perfect. A small bar 
is, when at the right heat, welded by a few quick blows ; and the 
time of the operation is not great enough to allow the iron to 
become cool. With a large bar it is different. It requires more 
and harder blows, and more time ; and, if at the right heat 
when the operation is begun, it may be too cool before it is 
ended, or, in order that it shall not be, it may be heated a 
little too much on the start ; the surface of the weld is greater, 
and is more exposed to the danger of interposition of ashes, 
dust, or scoria, either of which will prevent a perfect weld. 

Finally, if the cable be finished without any accidental 
defect, the proof of the 2!' so far exceeds that of the If', in 
proportion to its strength, that it is possible that the strength 
it may have had will be lowered by it. 

For the reasons assigned, we are of the opinion that the 
margin of safety secured by the use of a cable of If" iron, 
weighing twelve tons, is equally great as by the use of the 2'', 
weighing eighteen tons. 

II. The second method of reducing the weight of cables con- 
sists in the substitution of open for studded links. 

There exists a strong prejudice against the use of cables 
made from links without studs. This prejudice is based upon 
the opinion which is very generally entertained, that, first, the 
open link is not as strong as the studded one ; second, that, 
owing to the want of the support given to the sides by the stud 
when used, the open link will collapse at a much lower strain 
than the studded one will, and that this collapse will be so 
great that the links will nip each other, and become rigid ; and, 
third, that the liability of the relative position of the links to 
become misplaced is greater with the open than with the stud- 
ded links, from which cause jams may occur in the hawse-pipe 
when the cable is running out, or, after having remained some 
time with a slack cable, a sudden squall, tautening it, might 
produce the same effect. 



THE CABLE. 61 

The first of these objections, viz., that the open link is weaker 
than the studded one, our experiments show to be without foun- 
dation. The contrary is the case under all circumstances. 

We are led, by the results of our tests, to doubt that the 
second objection exists to the extent generally supposed. We 
find, that, in all cases, the open links begin to change form 
at a lower stress than the studded ones ; but the sides having 
straightened somewhat, the stress is soon resisted by the tena- 
city of the material itself, and unless the iron is very soft 
and ductile (much more so than is usually the case with chain- 
iron), the closure does not continue to be rapid ; and at an 
extreme stress, sufficient to rupture the studded link, if there 
be one in the section under test, the closure has not been so 
great as to unfit the open links for service. 

With irons F and O, both extremely ductile, some of the 
open links were too much closed for service, but others were 
not, after having resisted the stress which broke the studded 
links. Such iron, however, will not often be made into cables ; 
and we have, to a certain extent, a resource by which this early 
closure of the sides may be delayed with all irons. 

A cable made of bolts of | of an inch greater diameter, 
without studs, will possess fully twenty per cent more strength 
than the smaller studded cable, and will weigh but a trifle more. 
For instance, the total weight of 150 fathoms or ten sections 
of \l" studded cable would be 20,143 pouuds ; and that of 150 
fathoms or ten sections of li'' open cable would be 22,008 
pounds. 

Thus the difference in weight would be but 1,865 pounds. 

The probable strength of the 1^'' studded cable would be, at 
greatest, 157,000 pounds; that of the U^ if studded, 182,000 
pounds, and if unstudded considerably more ; the minimum 
difference of 25,000 pounds being nearly sixteen per cent of 
the entire strength of the 1^'' cable. And, as the action of 
the studs tends to pry open such welds as may not be perfect, 
the chances for regularity in strength are much increased by its 
omission. And it is more than probable that the extreme stress 



62 WROUGHT-IROX AND CHAIN-CABLES. 

at which the li'' would break would not close the links of 1|" 
to such extent as to render them unserviceable. 

The third objection to the use of open-link cables is that it is 
presumed that they are more liable to become fouled and 
kinked than the studded-link cable, while being stowed in the 
chain-locker, or when slack, and the vessel changes her position 
without tautening the cable. 

There are reasons based upon facts which actually exist, 
connected with the process of manufacture, which justify us 
in the assumption that the danger from this cause is not so 
great with open-link as with studded-link cables. [These 
reasons are given at length in the original report.] 

CoMPARisox OF Results obtained by Tension upon Sec- 
tions OF Cable-Links, and upon Baes of the Iron 
FPvOM which Links were made. 

It was considered that if there existed, as seemed probable, 
a relationship between the strength and other properties of the 
round bar, and those of the links made from it, it would be a 
valuable result to determine such relationship, and to find to 
how great an extent it could be depended upon, and within 
what margins it existed ; inasmuch as the simple and inexpen- 
sive test of tension upon a portion of a bar would provide data 
b}^ which the probable strength of a cable made from it could 
be judged. 

The following tables have been prepared for the purpose of 
developing this relationship, and finding its margins. 

We find that with iron of moderate tenacity, and witli good 
welding properties, the percentage of the bar's strength, which 
is carried with great uniformity into the link, is from 160 to 
175 per cent ; that, with irons of unsuitable qualities, this per- 
centage is frequently low and frequently high, it being very 
irregular, and averages of less than 155 per cent, made up of 
very irregular factors, are common ; and that Avith the best 
chain-iron, although there may be links which develop over 175 
per cent, such cases are rare. 



THE CABLE. 



63 



Comparison of Strength of Cable-Links and Round Bars. 

Iron A. 



Cable Links. 


Round Bars. 


Ratios of 
Links & Bars. 




rs 


Stress in Pounds. 




c 




Stress in Pounds. 


jo 








2 




• 




1 

6 


jq 












• 


i 

o 


'6 


O 
o 


"a 

1s| 


'6 

St 


O 

o 


O 1) 


2 

> s 


s 








^ ^ rt 


o j; £ 


o . 

1:3 


O 


IP 




c"'Sfc 

to 


rt <y cs 


.2 Js 


i c3 

o a 


O 


^ 


fo 


fc 


:^ 


•^ 


3S 


^ 


f^ 


fa 


Ch 


(§ 1 


tf 




1" 


3 


28,160 


71,328 


88,441 


39.5 


1.15" 


3 


28,127 


44,126 


54,690 


63.9 


61.9 


161.3 


n 


2 


37,920 


89,040 


88,773 ! 42.5 


1.15 


3 


27,488 


53,997 


53.900 


51.2 


60.6 


164.9 


n 


2 


47,040 


114,680 


92,689 I 41. 


1.2 


3 


33,888 


66,112 


53,879 


51.3 


57.7 


173.5 


n 


2 


58,080 


134,400 


91,180 


43.2 


1.5 


3 


49,600 


78,944 


53,557 


62.8 


58.7 


170.3 


n 


2 


68,650 


153,600 


86,926 


44.7 


1.65 


2 


50,880 


91,680 


51,884 


55.4 


59.7 


167.5 


n 


2 


76,320 


174,260 


84.551 


43.7 


1.35 


2 


66,240 


111,984 


54,334 


59.1 


64.3 


155.6 


n 


2 


86,400 


214,560 


89,213 


40.3 


1.85 


2 


70,840 


123,840 


51,509 


57.2 


57.6 


173. 


n 


1 


96,000 


252,960 


91,125 


38. 


2. 


2 


79,650 


141,120 


50,854 


56. 


56.7 


176. 


2 


n 




264,002 


84,023 





1.56 


9 


91,038 


157,588 


50,171 


57.8 


59. 


168.9 



Iron B. 



1t\ 13 


61,721 


149,790 


92,293 


41.1 


1.32 


4 


52,607 84,862 52,287 


61.8 


56.7 


iH 4 


87,937 


198,144 


86,637 


44.4 


1.23 


3 


74,113 118,273 52,895 


62.7 


59.9 


ni 4 


94,143 


221,650 


85,910 


41.5 





3 


87,743 137,023 53,109 


63. 


62.1 



176.4 
166.7 
161.7 















Iron C 














*u 


1 


48,600 


101,800 


102,414 


47.6 




2 


31,710 


57,125 


57,470 


55.5 


56.1 


178.2 


*1't 


2 


61,450 


123,450 


98,573 


49.8 




1 


39,840 


71,040 


57,897 


56. 


57.5 


173.6 


*1^ 


2 


75,850 


133,400 


89,831 


56.8 




1 


46,080 


81,600 


54,949 


56.4 


61.1 


163.4 


*1t\ 


1 




149,600 


92,175 


.... 




1 


53,000 


84,000 


51,756 


63.1 


56.1 


178. 


H 


7 


65,700 


157,900 


89,360 


44.4 




5 


61,440 


97,921 


55,404 


62.5 


61.2 


161.9 


n 


( 


82,229 


180,.500 


87,030 


45.5 




4 


68,880 


115,749 


55,879 


59.4 


64.4 


155.5 


n 


13 


90,554 


199,830 


83,009 


45.5 




5 


75,420 


130,835 


54,410 


57.1 


65.9 


153. 


Iron D. First Lot, 


*n 


•7 


37,200 


96,200 


96,780 


38.6 




2 


29,300 


54,360 


54,687 


53.9 1 


56.6 


176.3 


*n 





53,800 


123,800 


100,896 


43.1 






34,560 


68,160 


55,550 


50.7 


55. 


181. 


•18 


2 


57,600 


143,400 


96,.565 


39.8 






47,040 


81,600 


54,949 


57.6 


56.8 


175.7 


nh 


2 


71,800 


178,300 


100,905 


40.3 






48,960 


92,160 


52,155 


53.1 


51.6 


193.4 


*n 


1 


85,000 


199,700 


96,287 


42.5 






62,400 


111,360 


53,695 


56. 


55.7 


179.2 


•1.? 


1 


94,100 


231,400 


96,216 


41. 






66,900 


126,720 


52,699 


52.8 


54.7 


182.6 


*^ 


1 


94,600 


238,100 


86,236 


40. 






76,800 


142,080 


51,459 


54. 


59.6 


167.6 


*2 


1 


134,400 


276,500 


88,000 


48.5 






89,760 


160,700 


51,146 


55.8 


58.1 


172. 













Iron 


D. 


Second Lot. 














36,200 


79.200 


100,843 


45.7 


1.25 




26,300 


48.000 


61,115 


54.8 


60.6 


165. 


n 




45,000 


87.500 


88,814 


51.4 


1.55 




33,100 


58.700 


59,582 


56.4 


67. 


149. 


11 




55,200 


113,000 


90,617 


48.8 


1.60 




39,900 


72,.300 


57,979 


55.2 


64. 


156.3 


n 




71,500 


137,200 


91,711 


52.1 


2.25 




47,500 


86,800 


58,021 


54.7 


63.2 


158. 


I5 




80,100 


173.000 


97.906 


46.3 


2.50 




58.200 


101.200 


56,505 


57.5 i 


58.5 


170.8 


If 




90.000 


182,000 


88. .306 


49.5 


3. 




63.2(X) 


110..'i00 


53,614 


57.2 


60.7 


164.8 


n 




99.000 


204,000 


84,823 


48.5 


3.10 




76.700 


128,600 


53.472 


59.6 1 


63. 


158.6 


1^ 




112,300 


215,000 


76,468 


52.2 


3.75 




90,000 


149,000 


53,100 


60.5 


69.3 


144.2 


2 




116,000 


240,000 


77,947 


Not 


br'k'n 


2 


105,400 


145,950 


47,648 


72.3 


60.8 


164.4 



The tests marked * were upon single links, the others upon sections of cable. 



64 



WROUGHT-IRON AND CHAIN-CABLES. 



Iron E. 







Cable Links. 






Round Bars. 




Ratios of 
























Links&Bars. 






Stress in Pov 


mds. 


00 o 


s 


a 


Stress in Pounds. 


CO ''~' 








so 








-1 


<i 










P o 




. 


CS 

pq 


p 


'6 


^ 


— "rt 


p 






M 


-gs 


?^£ 




CM 


o 


-/> 


A > 


o 
o 


Sb.2 


1* C 
^ =3 


P 


1^ 




a 




.^11 




1^ 


i 


o 


10 








o . 




2 J3 

11 




o5 


O 'T 

^ ii c; 


.2 s 


ft 


^ 


s 


Ph 


aa 


— < 


m 


^ 


f-^ 


^ 


Ch 


25 


^j 


25 


*n 


4 


43,700 


87,650 


84,360 


49.9 






34,848 


55,152 


53,097 


63.1 1 


62.9 


158.9 


*n 


4 


44,625 


113,650 


91,138 1 39.3 






28,320 


67,200 


53,893 


42.1 


59.2 


169.1 


*n 


4 


54,500 


134,900 


88,925 i 40.4 






39,360 


79,296 


52,254 


49.6 


58.8 


170.2 


*n 


2 


68,650 


160,650 


90,916 i 42.7 






50,080 


97,920 


55,415 


59.3 


61. 


164. 


*it 


2 


72,250 


189,800 


90,991 [ 38.1 






57,792 


108,384 


51,940 


53.3 


57.1 


175.1 


*ij 


1 


91,000 


221,500 


92,099 1 41. 






63,840 


124,128 


51,606 


51.4 


56. 


178.4 


*i| 


2 


93,800 


233,600 


82,858 1 40.2 




2 


76,608 


142,991 


50,880 


53.5 


61.3 


163.2 



Iron F. First Lot. 



n 

n 
n 
n 

2 



28,500 
50,000 
51,000 
60,540 
71,000 
76,400 
83,500 
105,000 



86,400 
101,700 
119,000 
155,500 
174,700 
203,500 
230,900 
268,750 



87,698 33. 


.60 


3 


82,855 : 49.1 


.... 


2 


79,545 42.9 


.90 


2 


88,002 38.9 


1.00 


2 


84,764 40.6 


1.00 


2 


84,615 37.5 


1.90 


2 


83,177 i 36.1 


2.4 


2 


86,414 i 39.1 


.... 


2 



32,993 
39,360 
48,190 
56,640 
69,890 
77,520 
91,295 
85,950 



53,053 

64,990 

77,235 

91,875 

107,520 

121,920 

140,925 

152,260 



53,850 
52,970 
51,296 
51,994 
52,163 
50,690 
51,039 
48,956 



62.1 


1 61.4 


! 60.5 


63.9 


' 62.3 


64.9 


61.6 


59. 


64.9 


61.5 


63.5 


; 59.9 


64.7 


I 60.6 


56.4 


! 56.6 



162.8 

156.4 

154. 

169.2 

162.5 

166.9 

163.8 

176.5 



Iron F. Third Lot. 







35,600 


67,600 


84,372 


52.6 




2 


31,300 


41,600 


51,921 


75.2 


61.5 


162.4 


n 




47,600 


85,000 


84,745 


56. 




2 


35,600 


50,300 


50,149 


70.7 


59.1 


168.8 


1 1 




55,000 


107,600 


87,693 


51.1 




2 


48,600 


64,700 


52,729 


75.1 


60.1 


166. 


i| 




65,600 


128,600 


85,962 


51. 




2 


58,500 


78,300 


52,339 


74.7 


60.8 


164.2 


I5 




70,600 


150,500 


85,172 


47. 




2 


62.000 


89,800 


50,820 


69. 


59.6 


167.6 


ii 


.. 








.... 




2 


72,000 


103,500 


50,529 


69.5 


.... 




ii 




90,000 


1*97,600 


83,095 


45.5 




2 


85,500 


120,200 


50.547 


71.2 


60.8 


164.6 


ii 




90,000 


215,600 


78,514 


41.7 




2 


97,800 


136,600 


49,744 


71.7 


63.3 


15^.8 


2 




100,600 


233,600 


73,621 


43. 




2 


113,800 


151,900 


47,872 


74.8 


65. 


148.8 


1 


3 


1,533 


3,775 


76,003 


40.7 




1 




2,919 


59,585 


.... 


77.6 


129.3 


§ 


4 


3,875 


8,916 


80,647 


43.7 




4 


4,410 


5,949 


54,090 


74.1 


67.1 


149.9 


1 


3 


6,600 


16,933 


«6,100 


39.1 




1 


7,680 


10,343 


52,772 


74.3 


61.2 


163.7 


1 


2 


5,800 


25,400 


85,519 


20.9 




3 


10,834 


15,924 


52,051 


67.9 


62.7 


159.5 


3 


2 


10,000 


34,700 


74,460 


29. 




3 


16,748 


23,024 


50,764 


72.8 


66.9 


150.6 


1 


2 


15,805 


46,400 


74,999 






3 


21,097 


31,317 


50,716 


67.4 


67.7 


148.1 



Iron Fx. First Lot. 







34,800 


70,300 


86,036 


49.5 


1.12 


5 


27,680 


45,040 


55,770 


61.5 


64. 


156.8 


V, 




44,400 


81,400 


79,725 


54.5 


1.42 


5 


35,500 


57,620 


56,434 


61.5 


70.8 


141.2 






61,100 


111,000 


90,464 


55. 


1.70 


5 


43,100 


68,460 


55,253 


63. 


61.7 


162. 




78,000 


124,000 


82,887 


62.9 


2.25 


5 


50,480 


80,360 


52,968 


64.8 


62.8 


154.2 


^5 




80,000 


153,000 


88,593 


52.3 


2.15 


5 


60,620 


94,520 


53,491 


64.1 


61.8 


161.8 


If 




98,000 


168,000 


81,513 


58.3 


3.11 


5 


70,560 


110,140 


53,537 


64. 


65.6 


152.4 


IS 




100,000 


185,000 


76,923 


54. 


2.60 


5 


87,960 


129,500 


53,846 


67.9 


70. 


142.8 


1| 




110,800 


205,600 


74,063 


53.9 


2.90 


5 


98,920 


146,780 


52,875 


67.3 


71.4 


140. 


2 


1 


117,200 


240,000 


76,384 


Not 
br'k'n 


4.8 


5 


108,980 


163,420 


52,011 


66.6 


.... 


.... 



* The tests marked * were upon single links, the others upon sections of cable. 



THE CABLE. 



6b 



Iron Fx. Third Lot. 



Cable Links. 


Round Bars. 


Ratios of 
Links&Baes. 




■3 


Stress in Pounds. 


tc 6 


c 


c 


Stress in Pou 


nds. 


i-% 








cS 

■£ 

an 
o 

O 

d 










A 

2 
3 

o . 


to 
O 








«S 9 
2:3 


an 

•^ CD 

.2 rt 

cS'-' 




Cm 

o 

o 


n 


o 

o 


■^ 1 


O 

— ? 


o 
o 

rt ^ 


o 

rO 


II 

o a 

|3 






34,500 


69,600 


88,617 


49.6 




2 


28,500 


42,350 


53,915 


67.3 


' 60.8 


164.4 


n 




39,600 


86,000 


85,724 


46. 




2 


34,800 


54,300 


54,644 


63.5 


63.7 


157. 


ji 




49,000 


105,000 


84,202 


46.7 




2 


41,800 


66,400 


53,247 


62.9 


63.2 


158. 


ii 




60,000 


126,800 


83,586 


47.3 




2 


52,500 


80,000 


52,733 


65.6 


63. 


158.6 


li 




70,600 


152,800 


85,315 


46.2 




2 


62,400 


94,600 


52.819 


65.9 


61.9 


161.6 


ig 




83,000 


179,000 


85,769 


46.4 




2 


70,000 


111,300 


53,329 


62.9 


63.1 


160.8 


^T 




100,000 


190,600 


80,237 


.52.5 




2 


81,000 


126,100 


53,154 


64,8 


66.2 


151.2 


1| 




109,000 


229,000 


83,394 


47.6 




2 


96,200 


146,500 


53,361 


65.7 


64. 


156.4 


2 




118,000 


238,600 


75,938 


49.5 




2 


104,500 


159,500 


50,763 


65.5 


66.8 


149.6 



Iron G. 






160,100 
195,200 
215,200 



P0,605 
94,118 
89,480 



1 


62,600 


91,800 


51,958 1 68.1 


1 


69,100 


106,200 


51,205 65.6 


1 


87,200 


121,200 


50,.395 71.9 



57.3 I 174.4 

54.4 183.2 
56.3 I 177.6 



Iron II. 



*ii 

*1J 



1 

1 

1 


170,000 
204,100 
225,200 


96,208 
97,409 
93,638 


.... 


.... 


1 
1 
1 


53,000 
60,900 
67,000 


92,700 
108,500 
129,400 


52,462 57.1 
52,314 56.1 
53,800 51.7 


1 54.5 
53.2 
57.5 



183.4 

188. 
174. 



Iron J. 






1 
1 
1 




157,600 
120,000 
222,700 


89,190 
57,859 
92,600 


.... 


.... 


1 
1 
1 




90,200 
109,400 
128,100 


51,047 
52,748 
53,264 


.... 


57.2 
91.2 
57.5 



174.6 
109.6 
173.8 



Iron K. 



n 


1 


39,400 


84,500 


85,001 


46.6 


1.70 


3 


37,120 


60,096 


60,458 


61.7 


71.1 


140.6 


i\ 


1 


47,000 


96,000 


78,240 


49. 


.50 


2 


44,640 


72,960 


59,461 


61.1 


76. 


131.4 


li 


1 


58,000 


125,800 


84,714 


42.2 


.47 


2 


46,080 


82,848 


55,790 


55.6 


65.8 


150.6 


1^ 


1 


57,600 


143,000 


80,925 


31.2 


.87 


2 


59,040 


101,280 


57,317 


58.2 


70.8 


141.2 


Iff 


2 


72,900 


177,450 


85,559 


41. 


.86 


4 


72,640 


118,463 ! 57,132 


63.1 


66.8 


149.7 


4 


1 


72,500 


172,800 


71,850 


42. 


.65 


1 


79,680 


139,200 


57,874 


57.2 


80.5 


124.1 


1? 


1 


97,000 


246,800 


89,387 


39. 


1.00 


2 


85,680 


154,080 


55,803 


55.6 


62.4 


J60. 


2 


1 


104,000 


258,900 


82,400 


40. 


1.00 


2 


101,280 


191,520 


58,890 


52.8 


74. 


135.2 



Iron L. 



*ii 



193,200 
163,600 
254,600 



109,337 

78,881 
105,862 



50,500 
92,200 
87,200 



123,300 
139,200 
145,000 



69,779 
67,116 
60,291 



41. 

66. 
60. 



63.8 

85. 

56.9 



156.6 
116.2 
175.6 



Iron M. 



n 


6 


53,700 


117,716 


98,905 


45.7 


.... 


20 


••••»• 


65,960 


53,752 


« • • • 


57.3 


178.4 


n 


22 


59,390 


116,628 


78,341 


51.4 


.... 


115 


54,789 


83,300 


55,991 


65.8 


72.0 


140.5 


ih 


6 


71,700 


152,467 


86,270 


47.2 




162 


61,808 


97,250 


54,480 


62.9 


63.8 


159.3 


Is 


2 


(80,000 
(79,000 


125,000 
180,000 


60,270 

86,788 


64. 1 
43.7 i 


.... 


10 


74,510 


119,750 


57,402 


61.7 


.... 





* The tests marked * were uijon single links, the others upon sections of cable. 



66 



WEOUGHT-IEON AND CHAIN-CABLES. 



Iron M. Second Lot. 



Cable Links. 



w 



13 


Stress in Pounds. 


it) 
















ij 


'^3 




"cS 


a 


01 


M 


= « o 


■ji 


— o 


O 


«5- . 




O 00 


Q) . 




v« 


m ^ 


~ « 

r; " 


a . .a<1 


o 


ti 


2^ 


iOs 


!^ 


S 


fe 


M 



it? 






Round Bars. 



Stress in Pounds. 



£^ 






^ CS 
c >-• 

■z< 

" c 

3.- 

to 



0) 



u ^ ^ 



D 
cs O cS 



Ratios of 
Links&Baks. 



4'iJ 



1?C5 



o a 
13 



1-5- 



If 
iJ^i 

-^16 



ll3 



92,000 

to 

114,000 

77,000 

to 
117,000 
113,100 

to 
133,000 
155,000 

to 
169,000 
187,000 
207,000 
212,000 

to 
225,600 
210,000 

to 
228,000 
255,000 

to 
278,000 



75,244 

to 
92,909 
57,650 

to 
86,474 
76,094 

to 
89,562 
88,058 

to 
95,642 
90,175 
92,576 
88,149 

to 
93,804 
81,395 

to 
88,605 
81,158 

to 
91,661 



72,700 


59,248 


.... 


76,800 


56,761 


.... 


84,300 


56,777 


.... 


99,429 


56,270 


.... 


113,760 
127,700 


54,851 
57,115 





137,092 


57,003 


.... 


142,367 


55,181 


.... 


171,490 


54,580 


.... 



63.8126.6) 

to to J 
79.0,156.8) 
65.6100.3) 

to I to J 
99.7152.3) 
63.4|l34. ) 

to to } 
74.6ll57.7) 
58.8:156.4] 

to I to j 
63.9|169.9] 
60.8,164.4 
61. 7 1 162.1 
60.8154.7] 



to 

64,7 
61.4 

to 



to 
164.5] 
147.6) 

to } 



67.8167.6) 
61.7 148.6) 
to I to 5 
67.3162.1 



Iron iV. 



n 




45,000 


85,000 


84,915 


53. 


1.76 


2 


32,300 


56,200 


56,143 


57.5 


66.1 


151.2 


n 




58,000 


105,000 


85,574 


53.8 


2.06 


2 


40,800 


69,300 


56,478 


58.1 


66. 


151.4 


n 




70,100 


126,400 


84,492 


55.4 


2.52 


2 


50,300 


81,200 


54,277 


62. 


64.2 


155.4 


H 




80,000 


152,200 


87,270 


52.5 


2.77 


2 


60,500 


93,400 


53,555 


64.7 


61.4 


162.8 


Is 




96,200 


195,500 


92,566 


49.2 


3.60 


2 


75,800 


119,000 


56,344 


63.6 


60.9 


164.2 


n 




110,300 


201,100 


85,538 


54.8 


1.75 


2 


80,600 


129,350 


55,018 


62.3 


64.3 


161.8 


^ 




116,200 


223,700 


81,463 


51.9 


3.40 


2 


92,300 


140,150 


51,037 


66.1 


62.6 


159.6 


2 




118,000 


232,000 


73,116 


50.8 


2.60 


2 


103,000 


164,200 


51,748 


62.6 


70.8 


141.2 



Iron O. 







31,400 


68,000 


84,872 


46.2 








30,000 


46,000 


57,363 


65.2 


67.6 


n 




35,000 


80,900 


85,131 


43.3 








30,800 


50,400 


53,035 


61.1 


62.3 


H 




45,800 


95,500 


77,832 


48. 








36,900 


61,400 


50,040 


60.1 


64.3 






51,200 


125,400 


87,631 


40.8 








50,000 


72,400 


50,594 


69. 


57.7 


i| 


1 


60,000 


155,500 


86,823 


38.6 








58,000 


91,400 


50,919 


63.4 


58.8 




74,500 


180,000 


87,336 


41.4 








70,100 


108,000 


52,401 


64.9 


60. 


n 




90,000 


207,000 


89,070 


43.5 








75,000 


116,500 


50,129 


64.3 


56.3 


n 




102,000 


237,000 


87,288 


43. 








83,800 


129,000 


47,478 


65. 


54,4 


2 




119,800 


238,000 


75,747 


50.8 








98,700 


151,600 


48,249 


65.1 


63.7 



148. 

160.6 

155.6 

173.2 

170. 

166.6 

177.6 

183.8 

156. 



THE CABLE. 



67 



Iron P. 



n 

1-5- 

n 

n 

2 







Cable Links. 








Round Bars. 




Ratios of 
Links&Baus. 




1 
s 

'to 

O 
O 

J?; 


Stress in Pounds. 


llatio between first 
Stretch and Frac- 
ture. 


a 
o 

p 

o . 


00 


Stress in Pounds. 


ItiUio between Stress- 
es of first Stretch 
and Frai^ture. 




00 

1— < 


a 

n 

o 

;-l 
ai 

a 

CS 


First Stretch 
was observed. 


J4 
o 
o 

£ • 


Borne by end 
per square 
inch sectional 
at Area. 




O 

o 


pS :3 

c _ 



52,800 



6| 61,800 
l' 125,000 



112,320 
110,000 
134,592 
141,000 
134,592 
256,320 



88,612 


.... 




2 


91,317 


47.6 




94 


89,968 


.... 




1 


86,876 


43.8 




2 


74,196 


.... 




1 


80,000 


48.8 




1 



45,124 

48,550 
46,080 

53,760 
96,000 



70,704 


55,782 


61.4 




74,427 


54,518 


65.3 


.... 


78,624 


52,556 


58.6 


58.4 


89,300 


53,345 


.... 


.... 


95,904 


52,868 


56.1 


71.2 


59,840 


49,872 


63. 


62.4 



157.9 
i6o!4 



Iron P, Second Lot. 



1 
IS 

n 
n 
n 
n 
n 
n 

2 



38,000 

45,200 

50,400 

60,000 

73,600 

86,000 

106,000 

115,000 

129,000 



60,400 
76,000 
122,100 
118,400 
156,000 
199,000 
212,000 
233,000 
242,000 



78,461 
77,141 
94,871 
76,933 
85,950 
94,270 
86,143 
83,933 
Not bro 



62.9 








2 


59.5 








2 


43.1 








2 


50.7 








2 


47.2 








2 


43.2 








2 


50. 








2 


49.4 








2 


ken 








2 



30,200 
40,700 
47,450 
53,500 
60,650 
70,800 
82,400 
89,700 
101,150 



44,500 

56,500 

73,200 

85,000 

98,300 

117,500 

130,050 

145,200 

161,300 



57,807 


67.9 


73.7 


57,289 


72. 


• • • • 


56,876 


64.8 


60. 


55,230 


62.9 


71.6 


54,159 


61.7 ! 


63. 


55,634 


60.2 


75.3 


52,844 


63.4 ' 


61.3 


52,305 


61.8 1 


62.3 


50,834 


62.7 1 


.... 



135.8 

im.s 

139.6 

158.6 

169.4 

163. 

160.4 



Iron Px. 



n 




53,000 


116,000 


93,023 


45.7 


.... 


2 


42,300 


70,250 


56,334 


59.5 


60.6 


165.2 


1^ 




71,400 


156,000 


87,102 


45.8 


.... 


2 


62,000 


97,350 


54.354 


64. 


62.4 


160.2 


1^ 




84,600 


196,200 


91,003 


43.1 


.... 


2 


70,600 


115,500 


54,689 


61.1 


58.8 


169.9 


1^ 




98,000 


209,800 


86,231 


46.7 


.... 


2 


82,500 


131,900 


54,212 


62.5 


63.1 


158.4 


n 




108,200 


236,000 


85,943 


45.8 


.... 


2 


88,600 


142,000 


51,762 


62.2 


60. 


166.2 


2 




120,000 


242,000 


Not bro 


ken 


.... 


1 


98,600 


168,800 


53,198 


58.4 


.... 


.... 



68 WKOUGHT-IEOX AXD CHAIN-CABLES. 



SECTION YI. 

PROOF STRAINS FOR CHAIN-CABLES. 

Effects produced by the Use of the Strains pre- 
scribed BY the Admiralty Proof Table. — Discussion 
OF THE Principles upon which "Proof Strains" 

SHOULD BE based. — PrOOF TaBLE CALCULATED UPON 

SUCH Principles. 

A finished cable has 3'et a final ordeal to undergo before it 
is issued for service, — one which may prove disastrous to its 
value, even if it has escaped every danger that has accompanied 
its manufacture. It is to be '' proved ; " which means that each 
of the fifteen-fathom '' sections " of which it is composed is to be 
subjected to a tensional strain sufficient to make it probable that 
the presence of any defective links will be made manifest, that 
they may be removed, and replaced by others. 

As tension in excess will probably injure the cable, it becomes 
a matter of importance to fix upon a strain for each size, wiiich, 
while sufficient to insure the detection of unduly weak links, 
ivill not produce them. Most American manufacturers of cable 
use for each size a stress which is prescribed by the standard 
proof table of the British Admiralty ; and their cables are sold 
with a guaranty that they have been so proved. 

Our experiments lead us to doubt the wisdom of thus apply- 
ing this English standard to measure American material. We 
consider, that, as applied to cables made of American bar-iron, 
this standard is faulty in two important respects : — 

Firsts The stress prescribed by it for every size of cable is 
too great. 

Second^ The stresses for the different sizes are unequal in 
their proportion to the strength of the links. 



PEOOF STEAINS FOR CHAIN-CABLES. 



69 



And we assign the following reasons for these opinions : — 

First, The stress for all sizes is based upon the assumption 
that the cable bolts of all diameters possess a strength equal 
to sixty thousand pounds per square inch. Few bars of Ameri- 
can iron have this strength, and, when they have, their cost pre- 
cludes their use as cable-iron ; and, as has been shown in the 
investigations by tension, although this strength may be found 
in the small bars, it is not found in the large sizes of the same 
iron. 

Secondly, If the bars of all sizes did possess this strength, 
the "proof" is still too great; for it probably exceeds by a 
considerable amount the elastic limit of the links. 

The table as furnished to the committee by two prominent 
manufacturers, viz., Messrs. J. B. Carr & Co. of Troy, and Mr. 
H. L. Fearing of Boston, is herewith given, that the discussion 
which follows may be clearly understood. 



Size. 


Column 1. 

Stress in 


Column 2. 
Stress in 


Column 3. 
Stress in 




Tons. 


Pounds. 


Tons. 


Pounds. 


Tons. 


Pounds. 


1 " 

1-3- 

1-5- 

li 

1 5 

ll' 

113 

O 3 

"16 

2^ 

"4 


18 
20 
23 
26 
28 
30 
34 
37 
41 
44 
48 
52 

-60 
64 
(jS 
72 

80 

88 


40,320 

44,800 

51,520 

58,200 

62,720 

67,200 

76,160 

82,880 

91,800 

98,500 

107,520 

116,480 

125,440 

134,400 

143,360 

152,320 

161,280 

179,200 

197,120 


18 
20 
23 
25 
29 
31 
34 
37 
41 
43 
48 
51 
56 
59 
64 
68 
72 
76 
81.3 

91.1 


40,320 

44,800 

51,520 

55,960 

64.960 

61>,440 

76,160 

82,880 

91,800 

' 96,320 

107,520 

114,240 

125,440 

132.160 

143.360 

152,320 

161,280 

171,360 

181,120 

204,064 


18 

20.32 

22.78 

25.38 

28.12 

31.01 

34.03 

37.22 

40.50 

43.94 

47.53 

51.25 

55.12 

59.05 

63.38 

67.57 

72 

76.59 

81.28 

86.13 

91.11 


40,320 

45,517 

51,030 

56.857 

63,000 

69.457 

76.230 

83.317 

90,720 

98,437 

106,470 

114.817 

123,480 

132.275 

141.750 

151,357 

161.280 

171,517 

182.070 

192.937 

204,120 



70 



WROUGHT-IRON AND CHAIN-CABLES. 



The formula upon which column 3 is calculated is one 
embodied as a rule as follows : — 

" For proof of each size, square the number of eighths of an 
inch in the diameter of the bar, and multiply the result by 630," 
the result being the stress in pounds. Thus : V\ 8 eighths, 
squared = 64, and 64 X 630 =: 40,320 pounds." 

Our experiments show that the elastic limit of the large bars 
is generally lower than that of the small ones of the same iron. 
Hence the irregular effect of the proof strains becomes a danger- 
ous one. 

The practical and actual results which we have found to 
occur through the use of this table, and which have doubtless 
occurred with many cables proved by it, but which have not 
been founds are that the stress is so great that it always exceeds 
the elastic limit of the links, and frequently cracks them. 

A few such results will be given. Six sections, each five fath- 
oms in length, were made up from good chain-iron ; three were 
of 1|'', and three of 1|'': all were "proved " by the Admiralty 
Table, and after proof inspected in the shop ; all were "passed " 
as sound ; but upon examination by aid of a magnifying-glass 
fourteen of the 387 links were found to be cracked. 

In the following table the strength of the strongest and 
weakest links made from several of the best of the chain-irons 
we have examined is given, with the ratio borne to such 
strength by the Admiralty proof strains for the sizes : — 



Iron. 


Strength of Large 
Links. 


Admiralty 

Proof, 
percentage 

OF 


Strength of Small 
Links. 


Admiralty 

Proof, 
percentage 

OF 






s 
1 
5 


o 

1 


to 

C 

s 


t-5 

O 

1 


o 


o 
m 


o 


■ 1 


01 


A 

C 

D 

F 

N 

O 

P 


2" 

n 
n 
ii 
n 
n 


Pounds. 
283,000 
231,300 
215,000 
215,600 
225,700 
237,000 
233,000 


Pounds. 

248,000 
191,000 


57 

53 

66 

66 

63.3 

60 

60.8 


65 
64 


1 " 

n 


Pounds. 
72,670 
96,960 
79,200 
67,600 
85,600 
68,000 

122,100 


Pounds. 
69,600 

74,488 


55.5 

52.5 

51.3 

59.6 

60 

59.3 

51.2 


58 
65 


Average. . 


.... 






61. 


64.5 


.... 






55.6 


61.6 



PROOF STEAIXS FOR CHAIN-CABLES. 71 

Convinced by the evidence which has been given, that prov- 
ing American cables by this standard was a fruitful source of 
weakened cables, we were also aware, that, in recommending 
that it should be no longer used, we should, if the advice were 
followed, deprive manufacturers of good cables of a safeguard 
against competition by those who might unchecked use inferior 
iron. We have therefore considered it essential that we should 
provide a substitute which would, in our judgment, prescribe 
strains which would fully ^:>ror^ cables, and not be liable to 
injure them. We submit such a table, which is based upon the 
two principles, that a j^roof strain should not greatly exceed 
the elastic limit, and that the strength of a cable is equal only 
to that of its weakest link. In the preparation of this table it 
was first necessary for us to establish within reasonable limits 
the probable maximum and minimum strength of cables of 
various sizes, and the elastic limit of the links. Neither of 
these factors can be fixed definitely : there are many causes 
which tend to produce great differences, both in the strength 
and elastic limit of links made from the same bar. The most 
important of these causes is the liability of the welds, wliich 
at the best are the weak spots of all links, to lack uniformity ; 
and no rules can be given which will insure uniform work from 
a number of chain-welders. We were therefore compelled to 
base our table upon data which, at the best, could be considered 
as but indicating probabilities. 

Assuming as a standard of perfection the characteristics of a 
bar, which when made into a link should develop twice the origi- 
nal strength of the bar, we considered that the iron which ap- 
proached most closely and with uniformity this standard was 
that which should be considered as the most suitable for cables. 
We have the records of the strains at which a large number of 
bars in their normal condition were ruptured by tension, and of 
many sections of cable made from them, which are incorporated 
in the "Tables of Comparative Action of Bars and Links." 
From these tables we have made the following abstracts which 
enable us to arrive at conclusions as to the probable strength 
of cables made from irons varying in characteristics : — 



WROUGHT-IROX AND CHAIN-CABLES. 









ft 



^ N 



o S 



• 2 






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^ 








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CJ 





PEOOF STRAINS FOR CHAIX-CABLES. 



73 









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74 TTROUGHT-IRON" AND CHAIN-CABLES. 

We have the comparative records of 210 sections of cables 
broken by tension, which were made of fifteen different irons. 
Assuming that the utmost strength which can be found in a 
link is equal to 200 per cent of that of the bar from which it 
was made, we have a standard by which to compare the irons, 
and establish their relative value. Examining the abstracts by 
this standard, we find that 36 sections developed over 170 per 
cent of the bar's strength, 22 of them exceeded 175 per cent, 
9 exceeded 180 per cent, and only one exceeded 185 per cent. 

On the other hand, 67 sections developed less than 155 per 
cent, leaving 107, or over 50 per cent of the series, which 
developed between 155 and 170 per cent of the bar's strength ; 
and of these the average development was 163 per cent. 

The 210 sections of various irons can be reduced to 143 sec- 
tions of iron which may be considered as more or less suitable 
for cable, by eliminating the records of the 67 sections, which 
were broken at less than 155 per cent of the bar's strength, and 
at once deciding that they have no claim to be considered as 
having been made from suitable chain-iron. 

This we can do in many cases, and assign good reasons : 24 
sections were made from an iron (M) in which analysis demon- 
strated that phosphorus, copper, nickel, and in some cases 
chromium, occurred, and possibly reduced their welding values, 
as all the " low breaks " of this iron occurred " through the 
weld ; " eight were made from iron K, in which carbon was high, 
and ten from irons Fx and P, which w^ere known to have been 
overworked, leaving but 22 such percentages to be assigned to 
the chapter of accidents. From which data we conclude that 
bars of fairly good chain-iron will produce links whose strength 
wdll not be less than 155 per cent, and not over 170 per cent ; 
and that by a series of tests an average of not less than 163 per 
cent, made up of fairly uniform factors, should be expected. 

We have therefore adopted for our standard of strength and 
welding qualities combined, 170 per cent of the strength of the 
bar for a maximum, 163 per cent for an average, and 155 per 
cent for a minimum. Iron which in the link form develops the 



PEOOF STRAINS FOR CHAIN-CABLES. 75 

average, by results which do not vary greatly, we consider to be 
suitable ; that which falls below the average, or produces it by 
very irregular factors, we consider as unsuitable. 

It remains to decide upon the strength of bar, which will 
most probably produce links which will develop the largest and 
most uniform percentages. Our records again supply the re- 
quired data. We find the irons A, B, O, and F, which were low 
in tensile strength, sustained the process of manufacture into 
links with less loss of strength than did other irons which 
exceeded in this respect ; and with all of the series excess of 
tensile strength was accompanied by deficiency in strength and 
uniformity as cable. , 

We have therefore decided upon adopting a low tensile strength 
as a probable indication of a high iveldiyig value, and as shown 
by the relative order as judged by the power of resisting sud- 
den strains, of great resilience. 

In selecting the low tensile strength, we did not decide arbi- 
trarily in favor of the precedence which should be given to the 
^percentage of bar's strength developed by the links. We find 
that in many cases the actual strength of the links made from 
the bars of low tensile strength equals and exceeds that of 
others from much stronger bars. 

For example, iron K 2'' bar, tensile strength 58,900 pounds 
per square inch ; strength of link, 258,900 pounds. 

Iron A, tensile strength 2^' bar, 50,171 pounds ; strength of 
link, 265,000 pounds. 

Iron D, tensile strength 2" bar, 51,152 pounds ; strength of 
link, 276,500 pounds. 

Iron F, tensile strength 2"' bar, 48,956 pounds ; strength of 
link, 268,750 pounds. 

In recommending for cable-manufacture iron of this character, 
we are aware that in so doing we will come in contact with a 
widely-spread and deeply-rooted prejudice in favor of the strong 
bar as best adapted to make strong links. It undoubtedly would 
be so, were it not that great strength in the direction of the 
fibre is not found often to exist except through the effect of 



T6 WROUGHT-IRON AND CHAIN-CABLES. 

a great amount of work, which will cause the iron to be too 
expensive for cable-iron, or through the presence of various 
chemicals which increase tenacity at the expense of welding 
properties, thus unfitting it for use as cable-iron. 

We consider that our experiments justify us in recommend- 
ing as a suitable strength for a 2'' bar of chain-iron a mean 
between the margins found to exist in those bars whose record 
both in bar and link form has been just given ; and as the links 
of iron D, with tensile strength 51,152 pounds, and of iron F 
with 48,956 pounds, were equally good and strong, we adopt 
their mean of 50,000 pounds. And we find that iron A, which 
possesses nearly the medium strength as a bar (50,171 pounds), 
produces cable which is remarkably strong and uniform. 

Considering, then, that an iron is suitable, which, as a 2^' bar, 
has strength of 50,000 pounds per square inch, and that other 
irons whose variation from this strength does not exceed five per 
cent above or three per cent below are equally suitable, we have, 
in determining the strength for the other sizes, to avail ourselves 
of the information procured in the investigation of the action oL 
the rolls ; which is, in brief, that the proportional strength of the 
bars of the same material increases as the diameter decreases, 
and that the aggregate of the increase for the sixteen sizes (meas- 
uring by sixteenths of an inch between 2'' and 1'') is from four 
to six thousand pounds, produced b}^ steps which are made 
more or less irregular by irregularities in heating the piles. 

Using the mean of the aggregate of increase of our best and 
most uniform irons, we find that the strength per square inch 
of a bar of V^ diameter is about 5,600 pounds greater than that 
of the 2'\ and that, if the 2'' bar is equal to 50,000 pounds, it is 
probable the V^ will be equal to 55,600 pounds. 

It was necessary to connect these strengths assigned to the 
extremes by a series of successivel}^ increasing factors, the aggre' 
gate of which should equal 5,600 pounds. It was evident that 
a uniform co-efficient of increase for each of the sixteen reduc- 
tions could not be used, as the difference in strength produced by 
variations in reductions changed much less rapidly than did that 



PEOOF STRAINS FOR CHAIN-CABLES. 



77 



in the entire strength of the various-sized bars produced by 
variations in diameter. We therefore calculated a ratio which 
produced a constantly increasing co-efficient to be applied as 
the diameters decreased, with the results given in the table 
below ; each of which results is the correction to be added to 
the strength per square inch of any size in order to obtain that 
of the size ^'' less in diameter. 

Starting with 50,000 pounds as the strength of the 2", and 
adding the increasing co-efficient, we arrive at a strength per 
square inch for each size which agrees closely with that found 
in the best and most uniform chain-irons. The latter, however, 
being exposed to constant chances of irregularities from many 
causes, cannot be expected to coincide in strength very closely 
with any calculated table. 

Using the above factors of correction, we obtain the following 
table : — 

Probable Strength of Round Bars, calculated with an Alloivance for Variation in 
Strength due to Variation in Diameter. 





Strength of Bar. 


Size of 


Strength op Bar. 


Size of 














Bar. 


Per Square 


Coefficient 

nf 


Of Entire 


Bar. 


Per Square 


Coefficient 

of 
Increase. 


Of Entire 




Inch. 


Increase. 


Bar. 




Inch. 


Bar. 




Pounds. 


Pounds. 


Pounds. 




Pounds. 


Pounds. 


Pounds. 


2 " 


50,000 


245 


157,080 


h\ 


52,584 


357 


85,339 


HI 


245 


253 


148,137 


If 


941 


376 


78,607 


n 


498 


262 


139,430 


h\ 


53,317 


398 


72,133 


lit 


760 


273 


130,966 


H 


715 


423 


65,914 


If 


51,033 


284 


122,745 


l>fi 


54,138 


451 


59,958 


IH 


317 


296 


114,770 


4 


589 


484 


54,261 


15 


613 


309 


107,040 


IV 


55,073 


523 


48,800 


h% 


922 


323 


99,560 


1 


596 


, , 


43,665 


li 


52,245 


339 


92,322 











Accepting this rate of increase of strength as one which ap- 
proximates to the actual increase of tenacity of iron bars of 
decreasing diameter, we have used it in the calculation of our 
proof-table. 

A few examples will be given, which show conclusively that, 



78 



WKOUGHT-mON AND CHAIN-CABLES. 



by means of the corrections for variation in diameter given in 
the table, the strength of a bar of, say, 2'', can be closely esti- 
mated from the data fnrnished by the test of V bar. Selecting 
irons A, F, O, and P, which were qnite uniform, the strength 
of the 2'' bars was : — 

Actual strength A, 157,630 lbs.; F, 150,413 11)8.; O, 151,597 lbs.; P, 159,720 lbs. 

Calculated with correction A, 154,190 lbs. ; F, 151,346 lbs. ; O, 148,989 lbs. ; V, 163,800 lbs. 

Calculated without correction A, 181,836 lbs.; F, 163,136 lbs. ; O, 166,635 lbs. ; P, 181,600 lbs. 

The latter process involving an over-estimate of from 12,700 
to 24,200 pounds ; which error is reduced in two cases by the 
use of the corrections to an over-estimate of 4,080 and 933 
pounds, and in others to an under-estimate of 3,448 and 2,608 
pounds. 

The following table has been prepared, in which the aver- 
age strength of such bars as have produced good cables is 
placed in contrast with the strength called for by the calcu- 
lated table : — 

Comparison of Calculated loitli Actual Strength of Bars. 





Strength. 






Irons represented in Averages. 




Size 






Differ- 










of 
Bar. 














Calcu- 
lated. 


By actual 
Tests. 


ence. 


No. 

of 

Irons. 


No. 

of 

Tests. 


Name of Irons. 






Pounds. 


Pounds. 


Pounds. 










2 " 


157,080 


157,580 


500 


9 


35 


A, C, D, E, F, Fx, M, 0, P. 




m 


148,137 


.... 


.... 


.. 


.. 






H 


139,430 


141,120 


1,690 


9 


26 


Same as 2". 




Hf 


130,966 


131,975 


1,009 


5 


8 


B, C, E, G, H. 




if 


122,745 


124,580 


1,835 


13 


33 


A, C, D, E, F, G, H, J, Fx, 0, N, 


P, M. 


m 


114,770 


115,690 


920 


4 


7 


B, C,E, G. 




1 5 


107,040 


108,800 


1,760 


10 


25 


A, C, D, E, F, Fx, G, H, J, 0. 




h\ 


99,560 


.... 


.... 


.. 


.. 






H 


92,322 


93,358 


1,036 


13 


34 


Same as 1|". 




1^ 


85,339 


85,000 


339 


6 


12 


B, C, E, G, II, P. 




If 


78,607 


79,311 


704 


9 


27 


A, C, D, E, F, Fx, N, 0, P. 




h\ 


72,133 


74,505 


2,372 


1 


94 


P. 




H 


65,914 


66,724 


810 


'9 


106 


Same as 1|". 




h\ 


59,958 


.... 







.. 


' 




^ 


54,261 


54,570 


309 


9 


29 


Same as 1§". 




iiV 


48,800 


.... 


.... 


.. 








1 


43,665 


44,126 


461 


6 


26 


A, D, F, Fx, O, P. 





PEOOF STEAINS FOE CHAIN-CABLES. 



79 



Having thus fixed upon a suitable strength for each sized 
bar, we deduce the probable strength of cables made from 
them by the aid of the percentages of the bar's strength which 
we have found will probably be developed by the links, as 
indicated by those found in such irons as we have examined. 

In this table of strength of links it is considered that no iron 
should be expected to possess in link form over 170 per cent of 
the bar's strength, and that no suitable chain-iron should possess 
less than 155 per cent of the same ; and that the average strength 
of a number of tested sections should not be less than 163 per 
cent, such average to be made from fairly uniform factors. 

Probable Strejir/th of Cables made from Bars with Strength corresponding to 

that gicen in Table. 



Size of Bar. 


Strength of Entire 


Maximum, 


Average, 


Minimum, 


Bar. 


170 per cent of Bar. 


163 per cent of Bar. 


155 per cent of Bar. 




Pounds. 


Pounds. 


Pounds. 


Pounds. 


2" . . . 


157,080 


267,036 


256,040 


243,474 


m 








148,137 


251,833 


241,463 


229,612 


n 








139,430 


237,031 


227,271 


216,116 


m 








130,966 


222,642 


213,475 


202,997 


If 








122,745 


208,666 


200,074 


190,255 


iH 








114,770 


195.109 


187.075 


177,894 


If 








107,040 


181,968 


174,475 


165,912 


lA 








99.560 


169,250 


162,283 


154,318 


H 








92,322 


156,947 


150,485 


143,099 


ItV 








85,339 


145,076 


139,103 


132,275 


If 








78,607 


133,632 


128,129 


121,841 


ii% 








72,133 


122,626 


117,577 


111,806 


H 








65,914 


112,054 


107,440 


102,167 


1^ 








59,958 


101,929 


97,731 


92,935 


n 








54,261 


92,244 


88.445 


84,105 


iiV 








48.800 


82,960 


79,544 


75,640 


1. 








43,665 


74.230 


71,172 


67,681 



We have concluded that we cannot adopt a safer proof-strain 
than one which approximates to the elastic limit of the link ; 
and the link whose elastic limit we should adopt is the weakest 
one which will, after proof, remain in the cable. 

We have found by a great number of tests of bars in their 



80 WROTJGHT-IEON AND CHAIN-CABLES. 

normal condition, that the elastic limit of good cable-iron is 
about 57 per cent of its ultimate strength. 

The process by which the links are manufactured undoubt- 
edly changes both the strength and elastic limit of the portion 
upon which the welds are made : the extent of this change we 
have no means of knowing ; and so irregular are the processes 
of manufacture, that, if accurately ascertained in regard to a 
tested link, the data would be of no value in estimating its 
extent in the case of another. 

We are therefore again reduced to probabilities. Generally 
the elastic limit of material is coincident with the first percep- 
tible permanent change of form produced b}^ stress. With a 
chain-link this cannot be accepted as correct, as, through vari- 
ous causes, the form of the link may change at a stress not 
great* enough to produce change in the atomic relations of the 
material. Still, this first change of form indicates an approach 
to this limit ; and we have carefully observed it in the test of 
many links, and find that with such irons as A, B, C, F, Px, 
and others considered suitable for cable, the percentage of the 
stress which will break the cable, at which the elongation can 
be observed and measured, is about 44 per cent, and that this 
percentage exists with considerable regularity, so much so that 
we feel justified in assuming it as the nearest approximation to 
the elastic limit of the link that can be deduced from our ex- 
periments. But we believe, for several reasons, that in most 
cases it is too low a percentage : first of which is, that, tlirough 
badly fitting studs, many links during the beginning of an in- 
creasing stress may be considered as open or unstudded ones, 
and the " first stretch " is produced by a slight closure of the 
sides upon the stud ; and open links begin to stretch at a much 
lower stress than studded ones. It is probable that a mean be- 
tween the ratios of the ultimate strength at which the material 
in bar form begins to stretch, viz., 57 per cent, and that at 
which the links first elongate, viz., 44 per cent, will give as 
nearly the probable elastic limit of the link as can be obtained 
by any other process. No exact limit can be fixed upon. 



PROOF STRAINS FOR CHAIN-CABLES. 



81 



We have, therefore, in calculating the proof-strains, assumed 
that it is not safe to use fibove 50 per cent of the strength of 
the weakest part of the cable. 

The proving strains calculated upon the principles indicated 

are as follows : — 

Recommended Proof- Table: being equal to 45.57 per cent of the Strength of 
the Strongest, and to 50 per cent of that of the Wealcest, Links. 



Size. 



Inches. 



Ill 

n 

m 

If 
111 



Proving Strain. 



Pounds. 

121,737 

114,806 

108,058 

101,499 

95,128 

88,947 

82,956 

77,159 

71,550 



Tons. 

•^^•2 24 

^^224 
AQ 530 
^C>2 24 

^"^2 24 

^^ 2 2 4 
QQ \A3J- 
^^2 24 
Q7 7 6 
" * 2 2 4 
q_J 999 
"*2 24 
012110 

^^2Tro 



Size. 



Inches. 
1^ 

H 
H 

iiV 



Proving Strain. 



Pounds. 

66,138 
60,920 
55,903 
51,084 
46,468 
42,053 
37,820 
33,840 



Tons, 
oniill 

•"^2 24 
07 44 
- * 2 2 4 
04 2148 
-'■*2 24 
00 1 8 4 
'"'2240 
Or> 1 t) ti 8 
*''^2 24 
1 Q 1 7 3 3 
1^22T0 

1 f> 19 J_0 

-'^224 0" 
1 r: 2 4 

■^'^2240 



Comparison of the Proving Stra 


ins recommended, and 


Strains in 


Use. 






Probable Percent- 




Probable Percent- 






age of Strength 




age of 


Strength 


Size of 
Cable. 


Recommended 


OF — 


Admiralty 


OF — 




Proving 
Strain. 




Proving 
Strain. 






Strongest 


Weakest 


Strongest 


Weakest 






Link. 


Link, 




Link. 


Link. 


Inches. 


Pounds. 






Pounds. 




2 . . . 


121,737 


45.5 


50 


161.280 


60.3 


66.2 


lit" 






114,806 


45.5 


50 


151,-357 


60.1 


65.9 


n ■ 






108,058 


45.5 


50 


141,750 


59.8 


65.5 


111- 






101,499 


45.5 


50 


132,4.57 


59.4 


65.2 


If 






95,128 


45.5 


50 


123,480 


59.1 


64.9 


lU- 






88,947 


45.5 


50 


114,817 


58.8 


64.5 


^ 






82,956 


45.5 


50 


106,470 


58.5 


64.1 


1-1% 






77,159 


45.5 


50 


98.437 


58.2 


63.7 


H 






71,550 


45.5 


50 


90,720 


57.8 


63.3 


IV 






66,138 


45.5 


50 


83,317 


57.4 


62.9 


1 3 






60,920 


45.5 


50 


76,230 


57.0 


62.5 


i\ 






55,903 


45.5 


50 


69,457 


56.6 


62 1 


4 






51,084 


45.5 


50 


63,000 


56.2 


61.6 


i\ 






46,468 


45.5 


50 


56,857 


55.7 


61.1 


il 






42,053 


45.5 


50 


51,030 


55.3 


60.6 


iiV 






37,820 


45.5 


50 


45,517 


54.8 


60.1 


1 






33,840 


45.5 


50 


40,320 


54.3 


59.5 



82 WEOUGHT-IEON AND CHAIN-CABLES. 

The important points of difference between the recommended 
table and the one in use are : — 

First, In the former, the proof stress is, for every size, uni- 
form in its proportion to the probable strength of the links ; in 
the latter, it varies with every change of size. 

Second, Unless the elastic limit of the link is a greater pro- 
portion of its ultimate strength than that of the bar was of its 
strength, the strains of the table in use exceed this limit greatly, 
upon all sizes, while those of the former do not. 

Third, The recommended table recognizes the probability 
of there being introduced into cables links made from bars 
which, although of equally good iron as the rest, are, through 
fault in rolling, more or less scanty and, in consequence, possess 
less strength than bars rolled true ; which deficiency will be 
carried into the links. Should there, by accident, be a few 
links of 1||'' in a 2'' cable, the Admiralty proof would strain 
the strongest of such links to over 62 per cent, and the weakest 
to over 70 per cent, of the actual strength. 

For these reasons we recommend that this table, based upon 
actual strength of American iron, be used in place of that of 
the Admiralty. 



NOTES UPON THE IRONS EXAMINED. 83 



SECTIOISr YII. 

Part I. — Notes upon the Various Irons examined^ icitJi Experiments slioiuing 
Effects produced hy reworking Material of Different Characteristics. Part 
11. — Chemical Analyses of the Irons, loith Comparison of the Chemical and 
Physical Results. 

PART L — NOTES UPON THE IRONS EXAMINED. 

A COMPARISON of the results obtained by steady and sudden 
strains upon bars, and by steady strains upon the links made 
from the bars, indicates there are two classes of iron, which, 
although possessing considerable tensile strength in the form 
of straight bars, are equally unsuitable for cable-iron, through 
defective resilience, or inferior welding qualities. 

The first class includes the greater portion of the ordinary 
cheap iron found in the market, which is cheap because it has 
not received enough work which is expensive, to greatly change 
its characteristics from those which it possessed as crude iron. 

When tested by tension, iron of this class shows slight change 
of form at rupture ; and when broken by impact it proves brit- 
tle and unreliable. 

After fracture the appearance of the broken surface is de- 
scribed as " coarse granulous," and generally is bright and 
glistening. 

Such iron w^ill, when subjected to impact, break with but 
little deflection, and sometimes by blows of less force than it 
had previously withstood without sign of injury. 

The second class includes many excellent irons with high 
tenacity, which is due either to very thorough work, or to in- 



84 



WItOUGHT-IRON AND CHAIN-CABLES. 



greclients in its composition wliich tend to increase tenacity, 
frequently at the expense of welding qualities. 

A few notes in regard to the irons we have examined will 
illustrate these points. 

Contract Chain-Iron. 

The general character of this iron was that of class first, 
coarse, brittle, and slightly worked. 

As a result of the tests the entire stock on hand was con- 
demned ; but much of it having been found to be susceptible of 
great improvement by re-working, it was so treated with good 
results. 

Hammered Iron. 

The process by which this iron was manufactured was as 
follows : — 

Such of the contract chain-iron as our experiments had shown 
to be most benefited by increased work was selected, heated to 
a very high heat, and thoroughly hammered by the steam-ham- 
mer, each link or bolt by itself, until it was flattened to a slab. 
During the process great quantities of dross and scoria were 
expelled. 

Old condemned boilers were cut up, and the better portions 
cut into slabs, which were heated to a red heat, and the rust 
beaten off. ^hese slabs of the two irons were then piled in the 
following manner : — 



Boiler-iron. 


Twice 


-hammered chain 


-iron. 


Once- 


hammered chain- 


iron. 


Crown-sheet boiler-iron. 


Once- 


hammered chain- 


iron. 


Twice 


-hammered chain- 


■iron. 


Boiler-iron. 



NOTES UPON THE lEONS EXAMINED. 85 

These piles were about W by 10'', and were heated and ham- 
mered into octagonal irons. 

The advantages which it was hoped would be secured by the 
above method of piling were, that the soft and comparatively 
plastic centre would permit extreme flexure ; that the coarse, 
once-heated chain-iron Avould, being supported by this yielding 
centre, sustain flexure to a much greater extent than if not so 
supported ; and that the thoroughly re-heated and re-worked 
layers of chain-iron next to the outer layers would impart 
strength and toughness to the mass, and would absorb any 
blows or sudden strains, which received upon the outer surface 
would encounter first a cushion, and then a tough iron ; and 
that the resultant iron would possess great power to resist both 
sudden and steady strains, would bend double without breaking, 
and, the parts not being perfectly homogeneous, the rupture of 
a portion of a bar would not render valueless the remainder. 
That we secured all these advantages, our tests show plainly. 

Tested by tension, the iron showed fair tensile strength 
(average 53,000 pounds), uniformity, and ductility ; tested by 
impact, bars of all sizes in their normal condition would sustain 
heavy blows with slight deflection, and finally double till the 
sides were close together, without injury. Extreme tests were 
made by impact : one hundred and ninety-seven bars of 2'' diam- 
eter were swaged from the blooms, each of which was circled 
with a score -^ of an inch deep in the centre. These bars were 
struck upon this score by the wedge-shaped hammer of the 
impact testing machine, dropped from a height of thirty feet, 
the hammer weighing one hundred pounds. Each blow was 
considered to be equal to 3,000 foot-pounds. 

2, or 1 per cent, resisted 7 blows. 
5, or 2.54 per cent, resisted G blows. 
27, or 13.6 per cent, resisted 5 blows. 
G8, or 34.5 per cent, resisted 4 blows. 
71, or 36 per cent, resisted 3 blows. 
21, or 10 per cent, resisted 2 blows. 
3 broke at first blow. 



86 WEOUGHT-IEON AND CHAIN-CABLES. 

The three which broke at single blow were found to have 
been made partially of boiler-steel. 

Ieon a. 

From these hammered blooms, those which had resisted at 
least three blows were re-heated and rolled in the copper-mill 
into iron A. 

All the bars showed great ductility and change of form under 
tension, having a rather Ioav elastic limit, which was due, no 
doubt, to the fact that the softer and more ductile portions 
stretched first. Tested by impact, all sizes up to 21'^ bent com- 
pletely double by heavy blows (3,000 foot-pounds) delivered 
upon the centre of the test-pieces, bending them to the face of 
the w^edge, when the steam-hammer completed the closure. 

No iron which we have examined has proved suj^erior to 
this for cable-iron ; and there is no reason why any manu- 
facturer should not be able to produce similar material, by 
suitable mixtures in the piles, and by giving such amount of 
work as is found to be best adapted to develop good welding 
properties. 

Even though it should be considered as impractical to arrange 
every pile with due attention to a balancing of opposite char- 
acteristics, the quality of ordinary chain-iron can be vastly 
improved by subjecting the coarse material of which it is gen- 
erally composed to much more thorough Avorking than is ordi- 
narily the custom. 

Ieon B. 

Three bars of this iron, viz., lyf ^ ^ii'^ ^^^ -^iV' "^^re fur- 
nished as sample bars to compete for an order for chain-iron, 
with bars of irons C, E, G, H, I, J, K, and L, all of which are 
referred to as the " nine irons." By the result of the tests, this 
iron was accepted for the three sizes, the contractor having sub- 
stituted sam2~>les of iron B at the hist moment for those of iron 
L previously furnished, which proved red-short and worthless. 
This iron showed plainly the effect upon quality of increased 
reduction by the rolls, the smaller sizes being the most ductile 
and welded most firmly. 



NOTES UPOX THE IRONS EXAMINED. 87 



Iron C. 

Three bars of this iron, viz., If', If', and li'', were furnished 
to compete with the " nine irons ; " and upon the results of the 
tests this iron was received in the above sizes. 

The tests by tension and impact of the sample bars showed 
great ductility, low tensile strength, and remarkable toughness, 
with great power to resist impact. 

As cable the welding value was high, and the single links 
developed from 178 per cent to 199 per cent of the bar's 
strength, averaging 187 per cent. 

The iron delivered differed greatly from the samples : the 
tensile strength was higher ; and, although generally tough and 
strong, the characteristics of the iron delivered showed that it 
had received much less work than the samples, if of the same 
material. As cable links the IJ'' developed an average of 162 
per cent, the If 155 per cent, and the If 153 per cent, of the 
bar's strength, made up of very irregular factors, ranging from 
134 to 177 per cent. The If was brittle under impact, the 
If less so, and the If generally very tough. 

Iron D. 

Two lots of this iron, each consisting of nine bars from ^' to 
V\ were purchased for testing. Differences in the amount of 
reduction in the rolls produced with this iron very marked 
differences in strength, — the smaller bars having much greater 
tenacity than the larger ones. All sizes possessed great power 
to resist impact, except the 2'' bars, which were generally very 
brittle. 

It seems probable that the second lot, having been prepared 
expressly for test, received a great deal more work than the 
first. This overwork manifested itself both in increased tena- 
city and in decreased welding value ; the single links of the first 
lot developing an average of 178 per cent, and the sections of 
the second 158 per cent of the bar's strength. 

The 2'' bar of both lots differed greatly from all the smaller 



88 WROUGHT-IRON AND CHAIN-CABLES. 

bars, — so greatly that it was difficult to believe that they were 
of the same iron. Both were very brittle under impact, and 
when tested by tension, broke with almost imperceptible change 
of form, showing bright granulous surface of fracture. 

Iron E. 

The iron was all of good quality, moderate tensile strength 
tough under impact, and made good cable. 

This set of bars presented one peculiarity: the 1^'', instead 

of being of less tensile strength than the If, as is generally 

the case, was of greater ; and, on inquiry at the mill for the 

cause, we found that at this mill the pile used for the li'^ was 

of the same sectional area as that of the If, while at most 

mills it is less. 

Iron F. 

None of the bars furnished can be considered as chain-iron, for 
which purpose the manufacturers made a harder and stronger 
iron. We, however, tested many of them in the form of cables, 
considering that, in the records of such cables, we would find 
what could be expected of iron of very low tensile strength. 
F proved uniform under every form of test, the tensile strength, 
elongation, reduction of area, strength of links, and percentage 
of bar's strength developed by links, resistance to impact, and 
welding qualities, of any one lot, furnishing valuable evidence 
as to what might be expected of another. 

Iron Fx. 

The bars of this iron were rolled from piles made up of the 
same combination of crude irons as was used in the manufac- 
ture of iron F, but which piles were made to differ from those 
of F in sectional area. 

The proprietors of the rolling-mill furnished, without charge, 
all the facilities and material necessary to assist the committee 
in an investigation into the effects of the rolls ; the object of 
the experiments being the i)roduction of a set of bars, of 
various sizes, the tensile strength per square inch of which 
should be uniform. 



NOTES UPON THE IRONS EXAMINED. 89 

This result was accomplished, on the third trial, by so grad- 
uating the sectional areas of the various piles, that the areas of 
the bars rolled from them bore uniform ratios to those of the 
piles. (See the record of this experiment, page 18.) 

The resulting bars had received much more work than iron 
F; they had higher tenacity, equal if not superior resilience, 
but inferior welding qualities. 

Ikons G, H, I, and J. 

These bars were furnished to compete with the nine irons for 
a contract, but few tests were made upon them. 

G and H both proved of good fibrous material, sufficiently 
worked, and the few links made from them were strong ; G, as 
single links, being equal to 174 per cent, and H to 182 per 
cent, of the bar's strength. 

Iron I was thoroughly red-short ; and it was impossible to 
make links from it, they breaking while being bent. 

Six bars of iron J were furnished, which proved to be of a 
kind called in the shop "rotten." When tested by impact, 
with a sledge-hammer, the bars would split under the blows, 
showing smooth, black faces, resembling charcoal. 

Iron K. 

All the bars of this iron were of the same character, which 
was that of a fine-grained, thoroughlj^-worked, refined bar, of 
great tensile strength and uniformity, showing, when broken 
by any form of force, fine bright silvery fractures. 

The bars were so uniform in strength tliat they were selected 
as the material from which to make experiments which de- 
pended upon uniformity in character of material for their 
value. Under impact-tests, iron K gave peculiar results: if 
the skin was intact, a bar of ^' diameter could be doubled, 
cold, by heavy blows, without showing injury ; but if a 
slight score, or nick, was made in it, this power was entirely 
lost. 

The welding properties were not good, that is, by the ordi- 



90 WROUGHT-IRON AND CHAIN-CABLES. 

nary process. With some of the links, that were probably 
welded at suitable heat, the welds were firm, and they pos- 
sessed great strength ; but others, made from the same bars, 
broke at very low strains. 

The character of the material was so opposite to that of 
charcoal-bloom boiler-iron, each possessing valuable qualities 
which were lacking in the other, that it was resolved to make 
some experiments by mixing the two; and the results show 
plainly, that, by such admixture, iron superior for chain-cables 
to either of the constituents could be produced, and that ex- 
cellent chain-iron can be made by mills whose ordinary prod- 
ucts cannot be considered as suitable. 

Iron L. 

Five bars were furnished to compete with the nine irons. 
All forms of test indicated that the material was steel ; which 
analyses subsequently confirmed. The tensile strength was 
great ; reduction of area abrupt ; power of resistance to impact 
very slight when scored, but fair when not scored; welding- 
value low ; strength of links very irregular. 

Iron M. 

A great number of tests were made upon this iron, both by 
physical and chemical processes. It was delivered as chain- 
iron at a number of different times and lots. The bars of these 
lots varied greatly among themselves ; and the lots differed in 
many respects. 

As cable, the iron proved very defective and irregular. The 
trouble with it seemed to be, that, if not welded at exactly 
the right heat (a very low one), the part of the link upon 
which the weld was made lost its strength by the process, 
and in many cases, when tested, the links would- break 
through the weld at very low strains, showing little or no 
change of form, and the fractured ends remaining unreduced 
in diameter. 



NOTES UPON THE IRONS EXA]MINED. 91 



Iron N. 

The bars of this iron (eight in number) were furnished to 
the committee by a leading manufacturer as samples of " first- 
class chain-iron : " and they were probably a fair sample of the 
ordinary character of such chain-iron : tested by tension, the 
strength was generally high, change of form slight. 

Under impact, the large bars were very brittle, the 2" 
breaking by blows, Avhen unscored, which the If resisted after 
being scored. As cable, the If was superior to the 2''. 

The fault with this iron was too little work, the large bars 
receiving much less than the small ones. 

Iron O. 

This iron is in no sense of the word a chain-iron ; and its 
merits should not be- judged by its action in the form of cable. 

The material was soft charcoal-bloom, and of high price. 

It proved of value in our experiments upon the effect of the 
rolls, and as furnishing us with data as to the extreme of 
change of form which would occur to a link of very soft iron 
under stress. Although too ductile and soft for chain-iron, 
some of the larger sizes produced good links, while the smaller 
sizes were overworked for the purpose, and did not. 

Irons P and Px. 

These irons were made at the same rolling-mill, and when the 
physical tests were made upon Px it was considered to be of 
the same material as P; and the differences in their character- 
istics were attributed to variations in the mechanical processes 
by which they were produced, P having received one course 
of heating and hammering which was omitted with Px. Sub- 
sequently chemical analyses showed marked differences in the 
nature of the two irons. The results of the analyses were con- 
firmed by a letter from the manufacturer, in which he states 
that he jiterceives that the weak point of previous lots (iron P) 
was the lack of transverse strength when scored, and that he 



92 WEOUGHT-IEON AND CHALS^-CABLES. 

has in this lot (Px) overcome the difficulty, without essen- 
tially lowering the tensile strength. This w^as effected by, first, 
the selection and rigid puddling of pig-iron as free from phos- 
phorus as possible ; secondly, using a physic, which tended to 
eliminate the silicon and sulphur; and finally, the omission 
of the hammering. The result of these experiments by the 
manufacturer, to correct the defects found at the testing- 
machine, was the production of a superior chain-iron, which 
resisted impact well, and welded firmly. 



PART II. — COMPAKISON OF CHEMICAL AND PHYSICAL 

RESULTS. 

Variations in the physical qualities of iron may be due to 
different composition, or to different treatment in manufacture, 
or to both of these complex causes. In order to determine the 
specific causes of variation, one class of altering conditions 
should be made to vary largely, while the other class should 
be kept uniform. Then another class should be varied, and 
so on until the value of each is ascertained. As all the irons 
under consideration were intended to have that purity and 
refinement which was deemed indispensable in chain-cables, 
their chemical analyses are, perhaps, more important in proving 
that physical variations result chiefly from variations in treat- 
ment, than in pointing out the specific effects of certain in- 
gredients. While the subject of treatment — especially the 
increase of strength by greater reduction in rolling -;— may be 
the more important one, it can best be appreciated after we 
have familiarized ourselves wdth the general chemical and 
physical characters of the irons. The typical facts are given 
in the following tables : — 



COMPAEISOX OF CHE^nCAL AND PHYSICAL RESULTS. 93 





O 




a 




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COMPARISON OF CHEMICAL AND PHYSICAL RESULTS. 97 

Table I. Analyses of the irons. 

Table II. Relative values of irons in bars, in tenacity, reduc- 
tion of area, and elongation, and in proportion of chain to bar. 

Table III. Summary of principal physical and chemical char- 
acteristics of sixteen irons. 

Under the head of phosphorus, the leading chemical and 
physical facts about each iron likely to be affected by this 
element are compared, and then the group of irons is con- 
sidered, and a conclusion is reached ; under the head of silicon, 
the irons are again gone over in a similar manner ; and so on 
with carbon and other ingredients. A description of a few 
irons, in which composition should have the greatest influence 
on strength, will suffice to introduce these conclusions. 

Effects of Phosphorus. 

Iron O: P., 0.07; Si., 0.07; C, 0.04; slag, medium. 

Chemical impurities all very low. 

The iron had been thoroughly worked. 

Tenacity as bar and as link very low. 

Ductility as bar and as link very high. 

Welds very good. 

Low phosphorus does not alone account for these qualities. 
Iron F, with P. 0.20, Si. 0.16, and C. 0.03, has about the same 
tenacity and welding power, and approaches the same ductility. 
Iron P, with P. 0.25, Si. 0.18, and C. 0.033, has about equal 
ductility, but inferior welding qualities. Seeing that the 
thorough working of the small bars decreased welding power, 
as compared with that of the less compressed large bars, it is 
probable that method of manufacture is an important factor in 
all physical results. The effects of low phosphorus are not 
conspicuous. 

Iron P : P., 0.25 ; Si., 0.18 ; C, 0.03 ; slag, very low. 

P., rather high ; C, medium ; other impurities, low. 

Tenacity high as bar, irregular as link. 

Ductility high when not nicked, low when nicked. Welding 
value medium, through overwork, and possibly high P. 



98 WEOUGHT-IRON AND CHAIN-CABLES. 

Iron Px; P., 0.09; Si., 0.028; C, 0.066. 

This iron had the highest average of good qualities of the 
commercial bars examined, and was the best for general con- 
struction purposes. The characteristic effects of phosphorus 
might, previous to our investigation into the effects of reduc- 
tion, have been considered as shown by the behavior of two 
specimens, one of iron P, and one of Px, made in the same way, 
except that one course of piling and hammering was omitted 
from Px ; viz., — 

V^ bar-iron P : phosphorus, 0.25 ; tenacity, 57,807 pounds ; 
elongation, 19 per cent. 

If" bar-iron, Px : phosphorus, 0.09 ; tenacity, 54,212 pounds ; 
elongation, 24 per cent. 

But this increased tenacity and decreased ductility of the 
smaller bar are not due to P. alone : it had Si. 0.18 against 
Si. 0.03, and it had more reduction in the rolls. 

The difference in the tenacity of the bars of the same sizes 
of iron P, which may be considered as probably of similar 
composition, was nearly 5,000 pounds ; while between the bars 
in question, P and Px, it was but 3,600 pounds. 

Phosphorus may have affected the welding qualities and the 
ductility ; as iron Px, with much less of this element, welded 
much better, and had greater powers of resisting sudden strains, 
than iron P. 

Iron D: P., 0.18 (0.12 to 0.24); Si., 0.15; C, 0.03- slag, 
low. 

Carbon low, other impurities medium. 

Different bars very differently worked. 

Tenacity high as bar and link. 

Ductility medium as bar and link. 

Welds very good. 

There are various proofs that low phosphorus, even with low 
silicon, does not cause high ductility, and that the amount of 
reduction is the more important factor. For instance : — 

r' bar, P. 0.24, Si. 0.17, has tenacity per square inch, 61,000 
pounds ; elongation, 26 per cent. 



COMPAEISOX OF CHEMICAL AND PHYSICAL RESULTS. 99 

IV^ bar, P. 0.16, Si. 0.11, has tenacity per square inch, 56,000 
pounds ; elongation, 23 per cent. 

2'' bar, P. 0.21, Si. 0.16, has tenacity per square inch, 49,148 
pounds ; elongation, 0.07 per cent. 

The welds of the medium-sized and worked bars are the best, 
but all were good. No harmful effects of phosphorus can be 
traced in this iron. 

Iron B welded best, and had P. 0.23, and C. 0.015. 

Iron F; P., 0.20 ; Si., 0.16; C, 0.03: slag, low. 

Carbon low, other impurities medium. 

Iron suitabl}^ worked for welding, and very uniform. 

Tenacity as bar and as link very low. 

Ductility high. 

Welding power good. 

The remarkable uniformity of this iron proves it to have 
been made with great care, from selected materials. Why its 
tenacity is so low, it is difficult to say, on chemical grounds. 
The same iron, Fx, more worked, gives a medium tenacity, with 
substantially the same analysis. Iron A, with less P., Si., and 
C, is stronger. Iron E has lower P., the same Si., and only 0.02 
C, and yet a higher tenacity. 

Iron Fx (F more worked): P., 0.19; Si., 0.17; C, 0.03. 

Ingredients substantially the same as in F. 

Iron much more worked than F. 

Tenacity medium in link and bar. 

Ductility good. 

Welding power below medium. 

Iron B : P., 0.23 ; Si., 0.16 ; C, 0.015. 

P. rather high. Si. medium, and C. very low. 

Iron not sufficiently worked for strength. 

Tenacity rather low. 

Ductility quite low. 

Welds very good. 

Notwithstanding the extremely low C, the iron was not duc- 
tile. P. may well account for this, but not for low tenacity, as 
some of iron P had more P., and much higher tenacity. Low 



100 WEOUGHT-IEON AND CHAIX-CABLES. 

C. may partly account for low tenacity and good welds, but 
small reduction seems to be an equal cause. High P. did not 
prevent excellent welding. 

Iron M: P., 0.25 (0.21 to 0.32) ; Si., 0.18 (0.16 to 0.26) ; C, 
0.04; Ni., 0.18 (0.03 to 0.34) ; Cu., 0.34 (0.13 to 0.43); slag, 
various. 

P. rather high, Si. above medium, copper and nickel high, 
C. rather low. 

The amount of work the iron received can only be inferred 
from the sizes of the bars. 

Tenacity considerably above average. 

Ductility average. 

Welds weak. 

The character of this iron is so complex, and its physical 
character varies so much in the same-sized bars, that no satis- 
factory analysis of the data can be made. It seems certain 
from a comparison of the tables, that neither copper, nickel, 
cobalt, nor slag materially affected strength. The effects of 
these ingredients on welding will be considered under another 
head.* 

Conclusions about Pliospliorus. — The best of these irons 
average P. 0.09 to 0.20. The extreme limits are 0.065 and 
0.317. A soft boiler-plate steel might have the former amount ; 
the latter would give high tenacity and brittleness to even a 
low carbon steel. The investigations have been made so diffi- 
cult by the chemical similarity and general purity of most of 
the irons, and by their various degrees of reduction in roll- 
ing, that the effects of phosphorus cannot be independently 
traced. 

The phosphorus (average in each iron) runs very irregularly 
as follows, beginning with the highest of the following physi- 

* Chromium occurs only in iron M, four analyses of which show, Cr. 0.061 to 0.089. As this 
element is known to increase the tenacity of steel, it may have brought iron M up to a good 
standard of tenacity without helping its other stuctural qualities. These experiments give no 
absolute evidence as to the eft'ects of chromium; but it may be said that when mere tenacity is 
made the criterion of fitness, an iron like M may be found which will meet that requirement, and 
still prove untrustworthy for cables. 



COMPAKISON OF CHEMICAL AND PHYSICAL EESULTS. 101 

cal values : Tenacity, 0.72, 0.15, 0.20, 0.17, 0.22, 0.25, 0.19, 0.19, 
0.09, 0.15, 0.19, 0.23, 0.18, 0.20, 0.20, 0.07. Reduction of Area, 
0.07, 0.18, 0.09, 0.20, 0.15, 0.25, 0.19, 0.19, 0.20, 0.22, 0.17, 0.15, 
0.23, 0.19, 0.07, 0.20. Elongation, 0.09, 0.25, 0.07, 0.18, 0.19, 
0.20, 0.19, 0.22, 0.20, 0.19, 0.15, 0.17, 0.15, 0.23, 0.20, 0.07. 

It may be generally stated that pliosphorus 0.10, with carbon 
about 0.03, and silicon under 0.15, gave the best chain-cable 
irons of this group. One of the best irons, however, had P. 
0.23, although low tenacity and high ductility are the chief 
requirements of such irons. 

The effects of the different constituents on welding will be 
considered under that head. 

Effects of Silicon. 

See foregoing description, of irons O, P, F, and M. 

In iron F, which is among the highest in silicon, did this ele- 
ment cause the very low tenacity despite the fair amount of P. 
(0.20) ? If so. Si. must affect tenacity more than it affects duc- 
tility. But this is not the fact. In iron J, ductility as well as 
tenacity is made very low by high Si. (0.27). 

Iron J: Si., 0.27 (0.18 to 0.32); P., 0.20; C, 0.035; slag, 
average. 

Silicon high, other impurities medium. 

Iron not overworked. 

Tenacity very low in bar and link. 

Ductility very low in bar and link. 

Weld rather bad. 

There was no apparent chemical or physical cause for this 
low strength, except excessive silicon. Under sledge-blows the 
bars split as often as they broke off; and the faces of the fracture 
were like layers of charcoal, although both carbon and slag 
were medium. 

Conclusions about Silicon. — No ingredient of steel is less 
understood than this one. The technical managers of the 
Terrenoire Works in France, who have been notably successful 
in their steel manufactures founded on chemical induction, 



102 WROUGHT-IRON AND CHAIN-CABLES. 

especially in the manufacture of sound steel castings which 
contain a large amount of Si., believe that this ingredient, 
up to the amount contained in most of the irons we are con- 
sidering, does not decrease the tenacity or ductility of steel. 
And it is true that good steels are made by various processes 
with as much as 0.20 Si. It is believed by the Terrenoire 
managers that silica is the cause of the bad effects usually 
attributed to silicon. The table of analyses will show that in 
this case the ore has not been mistaken for the metal. The 
slag, which contains the silica, has been separately determined. 
Why wrought-iron should differ from steel in respect of the 
effects of Si., we have not so far been able to determine, if, 
indeed, it does so differ. It can only be said, with reference 
to this series of experiments, that there is an apparent decrease 
of strength due to an excess of this element, while the effects 
of medium amounts of it are overshadowed by larger causes. 
The extremes of Si. were 0.028 and 0.321. In the best irons 
it averaged about 0.15. It ran as follows, with a regularly 
decreasing order of value : In Tenacity^ Si., 0.09, 0.15, 0.15, 
0.15, 0.18, 0.18, 0.17, 0.16, 0.03, 0.16, 0.16, 0.16, 0.14, 0.27, 
0.16, 0.07. Reduction of Area, Si., 0.07, 0.14, 0.03, 0.16, 0.16, 
0.18, 0.16, 0.16, 0.15, 0.18, 0.15, 0.15, 0.16, 0.17, 0.09, 0.27. 
Elongation, Si., 0.03, 0.18, 0.07, 0.14, 0.16, 0.16, 0.16, 0.18, 0.15, 
0.17 0.16, 0.15, 0.15, 0.16, 0.27, 0.09. 

Effects of Caebon. 

See foregoing remarks on iron B, in which C. is extremely 
low. 

Iron L: C, average 0.35, highest 0.51; P., 0.10; Si., 0.10; 
slag, low. 

Carbon very high, other impurities quite low. 

Tenacity as bar highest. 

Ductility as bar and link lowest. 

Welding power most imperfect, decreasing as C increases. 

The following table,* from a paper by William Hackney, 

* Read before the Institution of Civil Engineers, London, April, 1S75. 



COMPARISON OF CHEMICAL AND PHYSICAL RESULTS. 103 



Esq., is valuable in this connection, as showing the amounts of 
C. in various well-known brands of wrought iron and steel. 

Percentages of Carbon in some Varieties of Iron and Steel. 



Sekies of the Irons. 



Description. 



Soft puddled iron 

Armor plates 

Iron rail 

Lowraoor boiler-plate .... 
Staftbrdshire boiler-plate . . 

Russian bar-iron 

Swedish iron bar 

Steely puddled iron .... 

Iron made by Catalan process 

direct from the ore .... 

Soft puddled steel 

Puddled steel rail 

Hard puddled steel .... 



Percentage of 
Carbon. 



Trace.* 

0.016 t 

0.033 t 

0.044 t 

0.091 

0.10 J 

0.19 t 

0.272 t 

0.340 t 

0.054 t 

0.087 t 

0.386 t 

0.30 to 0.40 1 
\ traces. f 
( 0.420 t 

0.501 1 

0.55 I 

1.380 t 



Series of the Steels. 



Description. 



Extra soft Fagersta Bessemer 
steel 

Extra soft Dowlais Bessemer 
steel 

Crewe boiler-plate steel, Bes 
semer process .... 

Locomotive crank-axles, Sera 
ing Bessemer steel ... 

Locomotive crank-axle, by 
Vickers, Shetiield . . . 

Rails and tires 

Bessemer spring steel . . 

Crucible steel : 
For masons' tools , . , 
For chipping chisels . . 
Crank-axle (by Krupp) , 
Gun (by Krupp) . . , 
For flat files 

Forged Indian wootz . . . 



Percentage of 
Carbon. 



j 0.085 § 
[ 0.135 II 

0.22 to 0.2411 

0.31 1 
0.49 I 

{0.46* 

0.30 to 0.50 
0.45 to 0.55 X 

0.6* 
0.75* 
1.05 t 
1.18 t 
1.20* 
1.645 1 



Iron L is, therefore, a so-called puddled steel, or more prop- 
erly a weld-steel. Since its impurities, other than C, are so 
small, it is impossible to avoid the conclusion that C. is the 
cause of its marked physical character. This is more plainly 
shown by the following : — 

1^ in. bar, C. 0.45, has nearly 70,000 pounds tenacity per square inch, and 

6.5 per cent elongation. 
1| in. bar, C. 51, has 67,000 pounds tenacity per square inch, and 6.5 per 

cent elongation. 
11^ and lif in. bar, C. 0.21 to 0.25, have average 58,000 pounds tenacity 

per square inch, and 13 per cent elongation. 

IronK: C, 0.07 ; P., C.15 ; Si., 0.15; slag, low. 
C. slightly high, other impurities medium. 
Iron well worked and very uniform. 
Tenacity as bar and link very high. 



* A. Willie. 
§ D. Forbes. 



t J. Percy. 
II Snelus. 



X A. Greiner. 
IT F. W. Webb. 



104 WEOUGHT-IEOX AND CHAIN-CABLES. 

Ductility below medium. 

Welding power quite low. 

The ductility was very fair when the bar was not nicked. 
The fracture was fine and silvery, like that of low steel. These 
facts, and the medium amounts of other impurities, point to C. 
as the hardening element. Irons having similar amounts of 
P. and Si., and low carbon, like irons A and C, have lower 
tenacity and higher ductility. 

Iron E: C, 0.018; P., 0.18; Si., 0.16. 

C. very low, other imj^urities medium. 

Tenacitv below avera^^e. 

Ductilitv hio'h. 

Welding power pretty good. 

These phenomena seem to be connected with low carbon. 

Conclusions about Carbon. — So much is known concerning 
the influence of C. on both wrought-iron and steel, that there 
is little danger of falling into error about it. The irons under 
consideration have C. almost exclusively low and pretty uni- 
form : the exceptional cases give very marked physical results, 
especially iron L, which is the only one really high in C. The 
other irons ranged between 0.015 and 0.07. Carbon ran with 
the following decreasing order of value in Tenacity : C. 0.35, 
0.068, 0.032, 0.042, 0.044, 0.033, 0.055, 0.032, 0.066, 0.032, 0.032, 
0.015, 0.02, 0.036, 0.026, 0.043. Reduction of Area, 0.043, 0.02, 
0.066, 0.026, 0.032, 0.033, 0.032, 0.032, 0.032, 0.044, 0.042, 
0.068, 0.015, 0.055, 0.35, 0.036. Elongation, 0.066, 0.033, 0.043, 
0.02, 0.032, 0.026, 0.032, 0.044, 0.032, 0.055, 0.032, 0.042, 0.068, 
0.015, 0.036, 0.35. 

It seems thus easy to vary the physical qualities of pud- 
dled iron by carbon ; but whether or not it is easy to uniformly 
vary the carbon in puddled iron, the checkered history of the 
" puddle d-sfe el " process will show. As we shall observe far- 
ther on, for uses in which the value of an iron depends on the 
strength of the particular kind of weld given to these links, 
C. must be under 0.04. But for uses in which the strength 
of the bar is the measure of fitness, C. may run up to 0.50 or 
more. 



COMPARISON OF CHEMICAl, AND PHYSICAL RESULTS. 105 

Blangmiese is so very low in all these irons, that its effects 
cannot be traced. It is highest in one lot of iron D, viz., 0.097 ; 
but even this could have little effect, in view of the fact that 
Mn. is often three times as high in very soft steels, and some- 
times runs above one per cent in low structural steels. Mn. 
seems to toughen steel, and to make it cast sound : its harden- 
ing effect up to Mn. 0.20 to 0.30 is slight. 

Copper is very low in all the irons, except M (Cu. 0.31 to 
0.43), which has about the average tenacity and ductility. Cu. 
is next highest (Cu. 0.17) in iron A, which has rather low 
tenacity, but very high ductility, on account of its low carbon 
(C. 0.02). These experiments furnish no evidence that copper 
affects strength. Its effect on welding will be further con- 
sidered. 

JSichel was only high (Ni. 0.34) in some of tlie bars of 
iron M, but did not appear to affect their strength. That 
it may have helped their welding capacity, is further re- 
ferred to. 

Cobalt was so low (Co. 0.11 maximum) that its effects on 
strength could not be traced. Possibly copper may have been 
neutralized by Ni. and Co. in its effect on strength, but these 
data are not evidence one Avay or the other. 

Sulphur was extremely low in all the irons, S. 0.046 being 
the highest percentage in one lot of iron M. So little S. did not 
affect welding power, as we shall observe farther on ; and it 
could hardly impair strength, when irons red-short from much 
S. are usually strong. 

Slag. — This averages about one per cent. It is lowest in 
iron L (slag 0.38), and highest in the 2'' bar of iron N (slag 
2.26). This bar had 51,700 pounds tenacity, and 8.7 per cent 
elongation; while the 1^'' bar of iron N, with 1.258 slag, had 
56,000 pounds tenacity, and 21.7 per cent elongation. Was 
this the result of too little work on the larger bar, or of tlie 
slag per se? Is the presence of much slag merely an indi- 
cation of too little work, — of a loose structure resulting from 
too little condensation of the fibres? Or does the slag, as slag. 



106 



WKOUGHT-IROX AXD CHAIN-CABLES. 



or clirt, exert an independent weakening influence ? Referring 
to the table of analyses we find : — 



Iron. 


Size. 


Slag. 


Iron. 


Size. 


Slag. 


L. . . 


*" 


0.668 


. . 


H" 


1.096 


L. 






&." 


0.388 


o . . 


13" 


0.974 


L. 






17" 

16 


0.192 


p . . 


1" 


0.848 


L. 






11" 


0.326 


p . . 


13" 


1.214 


L. 






15" 

8 


0.308 


D . . 


1" 


0.570 


L. 






111" 
16 


0.452 


D . . 


2" 


0.546 


L. 






113" 
■^16 


0.376 









It appears that the smallest and most worked iron often has 
the most slag. It is hence reasonable to conclude that an iron 
may be dirty and yet thoroughly condensed ; and it therefore 
seems probable that the 1^ bar of iron N was 4,300 pounds 
stronger than the 2'' bar, partly because it had one per cent 
less slag. The V^ bar of iron P had nearly 58,000 pounds tena- 
city; while the 1|'' bar of Px, with 0.40 more slag, had a little 
less than 53,000 pounds tenacity. It is, however, impossible to 
establish any close conclusions from these small variations of 
slag. The investigation requires analyses of irons equally 
worked, some of the specimens being purposely made very 

dirty. 

Welding. 

Before comparing the irons under this head, it may be well to 
briefly consider the heretofore ascertained facts, and the specu- 
lations which grow out of them. The generally received theory 
of welding is, that it is merely pressing the molecules of metal 
into contact, or rather into such proximity as they have in the 
other parts of the bar. Up to this point there can hardly be 
any difference of opinion, but here uncertainty begins. 

What impairs or prevents welding ? Is it merely the inter- 
position of foreign substances between the molecules of iron 
and any other substance which will enter into molecular rela- 
tions or vibrations with iron? Is it merely the mechanical 



COMPARISON OF CHEMICAL AND PHYSICAL RESULTS. 107 

preventing of contact between molecules, by the interposition 
of such substances ? This theory is based on such facts as the 
following : — 

1. Not only iron, but steel, has been so perfectly united 
that the seam could not be discovered, and that the strength 
was as great as it was at any point, by accurately planing 
and thoroughly smoothing and cleaning the surfaces, binding 
the two pieces together, subjecting them to a welding heat, 
and pressing them together by a very few hammer-blows. But 
when a thin film of oxide of irOn was placed between similar 
smooth surfaces, a weld could not be effected. 

2. Heterogeneous steel-scrap, having a much larger variation 
in composition than these irons have, when placed in a box 
composed of wrought-iron side and end pieces laid together, is 
(on a commercial scale) heated to the high temperature which 
the wrought-iron w411 stand, and then rolled into bars which 
are more homogeneous than ordinary wrought-iron. The 
wrought-iron box so settles together as the heat increases, that 
it nearly excludes the oxidizing atmosphere of the furnace, and 
no film of oxide of iron is interposed between the surfaces. At 
the same time the enclosed and more fusible steel is partially 
melted ; so that the impurities are partly forced out, and partly 
diffused throughout the mass, by the rolling. 

The other theory is, that the molecular motions of the iron 
are changed by the presence of certain impurities, such as cop- 
per and carbon, in such a manner that welding cannot occur or 
is greatly impaired. In favor of this theory it may be claimed 
that, say, two per cent of copper will almost prevent a weld ; 
while, if the interposition theory were true, this copper could 
only weaken the weld two per cent, as it could only cover two 
per cent of the surfaces of the molecules to be united. It is 
also stated that one per cent of carbon greatly impairs welding 
power, while the mere interposition of carbon should only 
reduce it one per cent. 

On the other hand, it may be claimed that in the perfect 
welding due to the fusion of cast-iron, the interposition of ten 



108 WKOUGHT-IRON AND CHAIN-CABLES. 

or even twenty per cent of impurities, such as carbon, silicon, 
and copper, does not affect the strength of the mass as much as 
one or two per cent of carbon or copper affects the strength of 
a weld made at a plastic instead of a fluid heat. It is also true 
that high tool steel, containing one and a half per cent of car- 
bon, is much stronger throughout its mass, all of which has 
been welded by fusion, than it would be if it had less carbon. 
Hence copper and carbon cannot impair the welding power of 
iron in any greater degree than by their interposition, provided 
the welding has the benefit of that perfect mohility which is due 
to fusion. The similar effect of partial fusion of steel in a 
wrought-iron box has already been mentioned. The inference is, 
that imperfect welding is not the result of a change in molecu- 
lar motions, due to impurities, but of imperfect mobility of the 
mass, — of not giving the molecules a chance to get together. 

Should it be suggested that the temperature of fusion, as 
compared with that of plasticity, may so change chemical affini- 
ties as to account for the different degrees of welding power, it 
may be answered that the temperature of fusion in one kind of 
iron is lower than that of plasticity in another, and that, as 
the welding and melting points of iron are largely due to the 
carbon they contain, such an impurity as copper, for instance, 
ought, on this theory, to impair welding in some cases, and not 
to affect it in others. This will be further referred to. 

The next inference would be, that by increasing temperature 
we chiefly improve the quality of welding. If temperature is 
increased to fusion, welding is practically perfect; if to plas- 
ticity and mobility of surfaces, welding should be nearly perfect. 

Then, how does it sometimes occur, that, the more, irons are 
heated, the worse they weld ? 

1. Not by reason of mere temperature ; for a heat almost to 
dissociation will fuse wrought-iron into a homogeneous mass. 

2. Probably by reason of oxidation, which, in a smith's fire 
especially, necessarily increases as the temperature increases. 
Even in a gas-furnace, a very hot flame is usually an oxidizing 
flame. The oxide of iron forms a dividing film between the 



COMPAEISOX OF CHEMICAL AND PHYSICAL RESULTS. 109 

surfaces to be joined ; while the slight interposition of the same 
oxide, when diffused throughout the mass by fusion or partial 
fusion, hardly affects welding. It is true that the contained 
slag, or the artificial flux, becomes " more fluid as the tempera- 
ture rises, and thus tends to wash away the oxide from the sur- 
faces ; but inasmuch as any iron, with any welding flux, can be 
oxidized till it scintillates, the value of a high heat in liquefy- 
ing the slag is more than balanced by its damage in burning 
the iron. 

3. But it still remains to be explained, why some irons weld 
at a higher temperature than others ; notably, why irons high 
in carbon, or in some other impurities, can only be welded 
soundly by ordinary processes at low heats. It can only be 
said that these impurities, as far as we are aware, increase the 
fusibility of iron, and that in an oxidizing flame oxidation be- 
comes more excessive as the point of fusion approaches. Weld- 
ing demands a certain condition of plasticity of surface : if this 
condition is not reached, welding fails for want of contact due 
to mobility ; if it is exceeded, welding fails for want of contact 
due to excessive oxidation. The temperature of this certain 
condition of plasticity varies with all the different composi- 
tions of irons. Hence, while it may be true that heterogeneous 
irons, which have different welding-points, cannot be soundly 
welded to one another in an oxidizing flame, it is not yet 
proved, nor is it probable, that homogeneous irons cannot be 
welded together, whatever their composition, even in an oxi- 
dizing flame. A collateral proof of this is, that one smith can 
weld irons and steels which another smith cannot weld at all, 
by means of a skilful selection of fluxes and a nice variation 
of temperatures. 

To recapitulate : It is certain that perfect welds are made by 
means of perfect contact due to fusion, and that nearly perfect 
welds are made by means of such contact as may be got by par- 
tial fusion in a non-oxidizing atmosphere or by the mechanical 
fitting of surfaces, whatever the composition of the iron may be 
v/ithin all known limits. While high temperature is thus the 



110 WROUGHT-IEOX AND CHAIN-CABLES. 

first cause of that mobility which promotes welding, it is also 
the cause, in an oxidizing atmosphere, of that " burning " which 
injures both the weld and the iron. Hence, welding in an oxi- 
dizing atmosphere must be done at a heat which gives a com- 
promise between imperfect contact due to want of mobility on 
the one hand, and imperfect contact due to oxidation on the 
other hand. This heat varies with each different composition 
of irons. It varies because these compositions change the 
fusing-points of irons, and hence their points of excessive oxi- 
dation. Hence, while ingredients such as carbon, jDhosphorus, 
copper, &c., positively do not prevent welding under fusion, or 
in a non-oxidizing atmosphere, it is probable that they impair it 
in an oxidizing atmosphere, not directly, but only by changing 
the susceptibility of the iron to oxidation. 

The obvious conclusions are : 1st, That any wrought-iron, 
of whatever ordinary composition, may be welded to itself in 
an oxidizing atmosphere at a certain temperature, which may 
differ very largely from that one which is vaguely known as 
"a welding heat." 2d, That in a non-oxidizing atmosphere, 
heterogeneous irons, however impure, may be soundly welded 
at indefinitely high temperatures. 

These speculations may throw little light on the subject of 
welding. They are introduced for the purpose of indicating 
the direction of further inquiry and experiment, and of im- 
pressing the necessity of caution in arriving at conclusions 
about these irons from the limited data afforded by these 
experiments. 

In reviewing the experiments with reference to welding, and 
under the precaution mentioned, let us observe ; — 

1st, All the irons were so very low in sulphur, that this 
ingredient could not have materially affected welding power. 

2d, As we shall see in detail, farther on, the irregular dif- 
ferences in the working and reduction of the bars, which 
affected all other ph3^sical properties, affected this one also. 

Let us first take the singularly impure iron M. Ite surfaces 
were pretty well united by welding, but the iron about the 



COMPAEISON OF CHEMICAL AND PHYSICAL RESULTS. Ill 

weld was weakened, especially at a high heat. Of 124 rup- 
tures of links made of this iron, 79 were through the weld, 
and the iron was little distorted. Of 311 ruptures of links 
made of other irons, but 37 were through the weld. 

The li' bar of iron M presents an exception: it stands 
high on the list in welding capacity, and contains copper 0.31 
(average Cu. in iron M, 0.34). Its ]3hosphorus, slag, and 
silicon are about average. But the bar is also remarkable in 
containing nickel 0.35, and cobalt 0.11. Did these ingredients 
neutralize the copper under this special treatment ? No other 
irons contain any notable amount of them, except iron A, 
which has Co. 0.07, and Ni. 0.08; but it also has Cu. 0.17.* 
The welds of this iron were very strong, the links breaking 
oftener at the butt than at the Aveld. 

Two links made from iron M were analyzed from specimens 
taken at the weld end and at the butt end. The weld end 
had been re-heated and hammered twice ; the butt end had 
not been hammered, and had received second heat only by 
conduction from the other end. The analj'ses show that silicon 
and slag only were materially affected by twice heating and 
hammering, as follows : — 



Silicon. 



Slag. 



Iron M, 1^ in. bar, weld end 
" Ig^ in. bar, butt end 
" If in. bar, weld end 
" If in. bar, butt end 



0.182 
0.203 
0.177 
0.261 



0.998 
1.074 
1.388 
1.732 



In oxidizing to silica, the Si. diffused a small amount of flux, 
which should have helped welding by preventing oxidation, or 
by carrying off oxide of iron, or both ; but the amount was so 
very small in this case that its effect cannot be traced. Nor 
does iron J, in which Si. was highest (0.18 to 0.32), confirm 

* This iron may have received the copper while being rolled in a train ordinarily used for 
copper, at the Xavy Yard, Washington, D.C., where it was manufactured. 



112 WEOUGHT-IRON AND CHAIN-CABLES. 

this theory. Although the other impurities were not high, and 
the iron was not overworked, it welded rather badly. The 
value of short chains is as follows : Best, Si. 0.16, 0.14, 0.07, 
0.03, 0.16, 0.15, 0.17, 0.15, 0.17, 0.18, 0.16, 0.18, 0.15, and, 
including J, 0.27. 

Phosphorus, up to the limit of i per cent, had not a notable 
effect on welding. It was lowest in iron O, which welded 
soundly ; but all impurities were low, and welding power was 
traced to the reduction of the bar by direct experiment. The 
same is true of iron P. Omitting one course of piling and 
hammering largely helped its welding power. Iron P Avelded 
badly, not necessarily on account of its P. 0.25 ; for iron B, 
with P. 0.23, and iron D, with P. 0.18, welded soundly. Iron 
^M had the high P. 0.23 (0.21 to 0.32). While its surfaces 
stuck together pretty well, the links broke through the weld 
when they were made at a high heat, which may be accounted 
for by the fact that phosphorus increases fluidity, and hence 
capacity for oxidation. The value of short chains is in the 
following order : Best, P. 0.23, 0.18, 0.07, 0.09, 0.20, 0.20, 0.19, 
0.17, 0.19, 0.25, 0.19, 0.22, 0.15. 

Carbon notably affected welding. It ran as follows in con- 
nection with regularly decreasing welding power : Best, C. 
0.015, 0.02, 0.043, 0.066, 0.026, 0.032, 0.032, 0.042, 0.055, 0.033, 
0.032, 0.044, 0.068, and including L, 0.351. 

The weld steel, or steely iron, L (C. 0.35), when treated by 
the uniform method usually adopted for chain-cable irons, made 
the worst welds. Iron K, with carbon so low as 0.07, made 
bad welds, although it was otherwise a good average chain- 
iron, with a medium amount of impurity. Carbon, in a greater 
degree than phosphorus, promotes fluidity : hence the iron is 
" burned " at the ordinary welding temperatures of low-carbon 
irons. 

Slag was highest (2.26 per cent) in the two-inch bar of iron 
N, which welded less soundly than any other bar of the same 
iron, and below average as compared with the other irons. 
Slag should theoretically improve welding, like any flux. 



COMPARISON OF CHEMICAL AND PHYSICAL RESULTS. 113 

but its effects in these experiments could not be definitely 
traced. 

What is learned from Chemical Analyses. 

So far, it may appear that little of use to the makers or 
the users of wrought-iron has been learned. But it should be 
remembered that all these irons were intended to be as nearly 
as possible alike, and to be adapted to the peculiar use of chain- 
cable. The makers generally understood the necessary condi- 
tions, and every effort was made to reach this special standard 
of excellence. Had it been reached, the irons would have all 
been exactly alike in physical character, and presumably similar, 
although not necessarily alike, in chemical character, for certain 
ingredients may replace others within limits which are perhaps 
narrow. Certainly the attempt to make all the irons conform 
to a well-known standard of quality was the worst possible 
way to ascertain the distinctive effects of the various altering 
ingredients. In order to make this latter determination, one 
series of irons should have been made as uniform as possible in 
all ingredients except one, for instance, phosphorus, and that 
one should have been varied as much as possible. Another 
series should have been alike except in silicon ; and so on, 
through the list of altering ingredients. The series of tests 
which the Board has undertaken on steels was devised upon 
this principle. It was, however, thought best, after the phj'si- 
cal tests of these irons were completed, to subject them to 
analysis, in the hope that some good result would follow. This 
hope has been realized in an unexpected and somewhat sur- 
prising manner. 

1st, The want of uniformity in the chemical composition of 
the same brand of iron is a conspicuous defect which is readily 
accounted for. In iron M, silicon varied from 0.16 to 0.26 ; 
in iron J, it varied from 0.18 to 0.32. In iron D, phosphorus 
varied from 0.12 to 0.24 ; and in iron J, from 0.11 to 0.29. 

Starting with a uniform pig-iron, the puddling process may 
or may not remove a large amount of silicon, phosphorus, and 



114 WEOUGHT-IRON AND CHAIN-CABLES. 

carbon, according to the temperature and agitation of the bath, 
the " fix " used in the furnace, and from many causes under the 
puddler's control, and dependent on his knowledge and skill. 

Such variations would be entirely inadmissible in the most 
common grades of steel : in fact, they could not occur in the 
cheap steel processes, when using a uniform pig-iron, except by 
a special effort. In the Bessemer process, the completion of 
the oxidation of silicon and carbon is obvious to the inexpert 
observer; in the open-hearth process, unmistakable tests are 
taken during the operation. The character of steel can be 
surely predicated on the analysis of its materials; that of 
wrought-iron is altered by subtle and unobserved causes. 
Should it be urged in favor of wrought-iron, that P. can be 
largely removed during its manufacture, while in the steel- 
manufacture it cannot be, it may be answered that there is an 
abundance of pig-irons which do not contain much P. ; and it is 
better to be sure of a definite amount of a deleterious ingre- 
dient than to run the risk of a variable amount. 

We are not prepared to show the exact effect of varying 
reduction on steel. Ingots of the same grade of steel, from six 
inches square to fourteen inches square, are emploj'cd for the 
same-sized bars ; the larger ones are preferred, notwithstanding 
the greater cost of working them, not because small ingots will 
not make good bars : but because they make too much scrap. 
Steel depends comparatively slightly on condensation for its 
density, but very greatly on its being cast from a fluid state. 
It is a crystalline mass in both large and small ingots, and not 
a bundle of fibres of iron more or less compacted. 

2d, This matter of varying strength due to varying reduction 

— the most important developed by the series of experiments 

— is made all the more certain and useful by the analyses ; for, 
without a knowledge of the composition of the bars and of the 
specific effects of different ingredients, a part of the variation 
now traced to reduction might have been attributed to com- 
position. 

It may be stated in general terms, that, notwithstanding this 



COMPAETSON OF CHEMICAL AND PHYSICAL EESULTS. 115 

attempt at uniformity, the differences in reduction in the roll- 
ing-mill from pile to bar caused as much variation in the 
physical qualities of these irons as did the differences in the 
chemical composition of the whole series of irons, excepting 
the steely iron L. The highest difference in tenacity, due 
apparently to varying reductions, is 11,969 pounds per square 
inch. The highest difference between the average tensional 
resistances of all the irons (excepting the steely iron L), due 
to all causes, is but 7,109 pounds. The following illustrations 
are more in detail : — 

Iron P. 

Tenacity of 1 in. bar (1.74 per cent of pile) above 2 in. (6.98 per cent of pile) . 
Elastic limit " " " " " " 

Iron F. Second Lot. 

Tenacity of IJ in. bar (2.76 per cent of pile) over 2 in. (5.23 per cent of pile) 
Elastic limit " '♦ " " '« " 

Iron F. Third Lot. 
Tenacity of I in. bar (1.60 per cent of pile) o%'er 2\ in. (6.13 per cent of pile) 
" g in. bar (3.68 per cent of pile) over 4 in. (15.70 per cent of pile) 

Elasticlimitof g in.bar " " " «« " 

Tenacity of 1 in. bar (3.14 per cent of pile) " •' " 

Iron N". 
Tenacity of 1^ in. bar (6.62 per cent of pile) above 2 in. (11.36 per cent of pile) . . 4,395 lbs. 

Iron A. 
Tenacity of 1 in. bar (3.14 per cent of pile) over 2 in. (8.72 per cent of pile) . . 4,519 lbs. 

Iro7i D. 
Difference in phosphorus in 1 in. and 2 in. bars, 0.026; other ingredients about alike. 
Tenacity of 1 in. bar over 2 in. bar 11,969 lbs. 

The following are apparently results of composition : — 

Comparative Tenacity. 
Of iron highest in average qualities over the one lowest in impurities .... 3,136 lbs. 
Of most tenacious steely iron (carbon 0.35) over least tenacious (carbon 0.04) . . 15,464 lbs. 

3d, The variation of welding power by reduction, in a 
greater degree than by composition, has already been shown in 
detail. Chemical analyses were necessary to establish this fact. 

4th, To the steel maker and user it will appear somewhat 
remarkable, that phosphorus may run up to nearly a quarter of 
one per cent in good chain-cable irons, when it is considered 



Per Sq. In. 


6,973 lbs. 


7,352 lbs. 


4,698 lbs. 


3,227 lbs. 


9,656 lbs. 


7,786 lbs. 


15,045 lbs. 


4,806 lbs. 



116 WEOUGHT-IRON AST) CHAIX-CABLES. 

that low tenacity and high ductility are the essential features 
of such irons, and that the effect of this ingredient is to pro- 
duce exactly opposite results. Suitable working probably 
counterbalanced its effects. 

5th, The comparison of chemical and physical results sug- 
gests a number of experiments which would go far to settle 
vexed questions, and improve the practice, especially with 
regard to welding. 

(1) Regarding slag, it has been shown that a larger amount 
is sometimes found in a well-worked than in a less-reduced iron, 
and that its effects are uncertain. Experiments should be 
arranged to show what composition of slags will readily come 
out of the pile in rolling ; whether two-high or three-high trains 
will best remove them, and how much and what kind of slaof 
affects strength and welding. A stable oxide of iron, which 
would probably do the most harm, could be formed b}- blowing 
superheated steam upon red-hot bars before piling. It might 
be proved that very fusible slags, or fluxes, should be placed in 
the pile to protect surfaces from oxidation, and to wash away 
less fusible impurities. 

(2) It has already been suggested that special irons, having 
respectively a certain ingredient in excess and the others low 
and uniform, should be made, in order to ascertain, in a con- 
spicuous manner, the physical effects of the various ingredients. 

(3) Referring to a previous recapitulation of remarks on 
welding : The effects of very different temperatures on irons 
varying in composition, as compared with that uniformly high 
temperature, usually known as a " welding heat," should be 
much more carefully ascertained. And the effects, and more 
especially the means of welding in a non-oxidizing flame, where 
mobility of surfaces can be got without '' burning," should be 
made the subject of elaborate experiments. The excellent 
welding of a heterogeneous mass of steel and iron, protected 
from oxidation by being placed in an iron box which will stand 
a high heat, has been referred to. The system of gas-welding 
by which Mr. Bertram welded boilers at Woolwich twenty 



COMPAEISOX OF CHEMICAL AXD PHYSICAL RESULTS. 117 

years ago has since been in regular use by the Butterly Com- 
pany, in England, for joining the members of wrought-iron 
beams of large section. It should seem within the power of 
modern engineering and chemistry to provide means for the 
perfection in a non-oxidizing atmosphere, of welds, like those 
of ships' cables and bridge-links, upon which hang so many 
lives and so much treasure. 

Conclusions DERrvT:D from a Co:mpartsox of Chemical 

AND Physical Results. 

I. Although most of the irons under consideration are much 
alike in composition, the hardening effects of phosphorus and 
silicon can be traced, and that of carbon is very obvious. Phos- 
phorus up to 0.10 per cent does not harm, and probably im- 
proves, irons containing silicon not above 0.15, and carbon not 
above 0.03. Kone of the ingredients except carbon in the pro- 
portions present seem to very notably affect welding by ordi- 
nary methods. 

II. The strength of wrought-iron and its welding power by 
ordinary methods are varied more by the amount of its reduc- 
tion in rolling than by its ordinary differences in composition. 
Uniform strength may be promoted by uniform reduction, but 
only at such increased cost of manufacture that the practice is 
not likely to obtain. Therefore the reduced strength of large 
bars made by ordinary methods should be considered in design- 
ing machinery and structures. 

III. In accordance with these facts the United-States Test 
Board has shown, by trial, the unsafety of the Admiralty proof- 
tables for chain-cable,. and has prepared new ones, and also new 
tables of the strength of different-sized bars. The Board has 
demonstrated that the tenacity of two-inch bar for chain-cable 
should be between 48,000 and 52,000 pounds per square inch, 
and of one-inch bar between 53,000 and 57,000 pounds ; and 
that stronger irons than these make worse cables, because they 
have low ductility and welding power. 

IV. Chemical analyses, made in connection with physical 



118 • WROUGHT-mOM AND CHAIN-CABLES. 

tests, are indispensable to conclusions about either the charac- 
ter or treatment of iron. In this series of experiments the 
demonstration that strength is dependent on reduction is made 
more definite and useful by the anal3"ses. 

Y. Analyses also prove that the same brand of wrought-iron 
may be heterogeneous in composition ; and they empliasize the 
previously known fact that wrought-iron making processes, as 
compared with the cheap steel processes, necessarily give an 
uncertain character to the former material, while to the latter 
the desired quality may be imparted with certainty and uni- 
formity. 

VI. The ordinary practice of welding is capable of radical 
improvement : the fact has been fully demonstrated; the means 
should be made the subject of complete experiments. The per- 
fection of means for welding in a non-oxidizing atmosphere 
would seem to be the promising direction of improvement. 

In submitting the foregoing history of their experiments, and 
deductions therefrom, the committees recognize the fact that 
much still remains to be done before either of the investigations 
can be considered complete. But, having exhausted the time 
and means at their disposal, they are compelled to submit the 
results as far as accomplished. 

L. A. BEARDSLEE, 
Commander U.S.N., Chairman of Committees D, H, and M. 

Q. A. GILLMORE, 

Lieut.-CoL, Corps of Engineers, Brev. Major-Gen., U.S.A., Chair- 
man of Committee B, Member of Committee D. 

A. L. HOLLEY, C.E., LL.D., 

Chairman of Committee C, Member of Committee H. 

WM. SOOY SMITH, C.E., 

Chairman of Committees E and K, Member of Committees H and M. 

DAVID SMITH, 

Chief Enr/ineer U.S.N., Chairman of Committee 0, Member of 
Committees D and M. 



NOTE BY THE ABEIDGER. 119 

[Note by the ABEn)GER.] The committees referred to 
in the signatures above were charged with the following divis- 
ions of the general work of the Board : — 

D. On chains and wire rope. \ 

H. On iron, malleable. >• The committees making this report. 

M. On re-heating and re-rolling. ) 

B. On armor-plate. "] 

C. On chemical research. • The reports of these committees 

E. On corrosion of metals. T have not yet been published. 
K. On orthogonal simultaneous strains. J 



